Remove autoconfigured (didn't work as implemented).

Primarily intended for use in libraries or other contexts where you want
to fall back to std/logging if the application is not using or hasn't
configured namespaced_logging.

By default the StdLoggingAppender only logs when no namespaced_logging
appenders are configured, but it can also be configured to always
forward log messages, even when namespaced_logging is configured.

.gitignore

@@ -3,3 +3,4 @@ nimcache/
 tests/tests
 src/namespaced_logging.out
 src/namespaced_logging/autoconfigured
+.worktrees

README.md

@@ -1,36 +1,79 @@
 # Namespaced Logging for Nim
 
-`namespaced_logging` provides a logging framework similar to [log4j][] or
+`namespaced_logging` is intended to be a high-performance, thread-safe logging
-[logback][] for Nim. It has three main motivating features:
+framework similar to [std/logging][std-logging] with support for
+namespace-scoped logging similar to [log4j][] or [logback][] for Nim. It has
+four main motivating features:
 - Hierarchical, namespaced logging
 - Safe and straightforward to use in multi-threaded applications.
-- Native support for structured logging (old-style string logging is also
+- Native support for structured logging.
-  supported).
+- Simple, autoconfigured usage pattern reminiscent of the
+  [std/logging][std-logging] interface (*not yet implemented*)
 
 ## Getting Started
 
-Install the package from nimble:
+Install the package via nimble:
 
 ```bash
-nimble install namespaced_logging
+# Not yet in official Nim packages. TODO once we've battle-tested it a little
+nimble install https://github.com/jdbernard/nim-namespaced-logging
 ```
 
-Then, in your application, you can use the logging system like so:
+## Usage Patterns
 
+### Manual Configuration
 ```nim
 import namespaced_logging
 
-# On the main thread
+# Manually creating a LogService. This is an independent logging root fully
-let logService = initLogService()
+# isolated from subsequent LogServices initialized with initLogService
-logService.addAppender(initConsoleAppender(LogLevel.INFO))
+var ls = initLogService()
 
-# On any thread, including the main thread
+# Configure logging
-let logger = logService.getLogger("app/service/example")
+ls.addAppender(initConsoleLogAppender())
-logger.info("Log from the example service")
+ls.addAppender(initFileLogAppender("app.log"))
+ls.setThreshold("api", lvlWarn)
 
-# Only get logs at the WARN or higher level from the database module
+# Create loggers
-let logger = logService.getLogger("app/database", threshold = some(Level.lvlWarn))
+let localLogSvc = threadLocalRef(ls)
-logger.error("Database connection failed")
+let apiLogger = localLogSvc.getLogger("api")
+let dbLogger = localLogSvc.getLogger("db")
+```
+
+### Manual Multithreaded Application
+```nim
+import namespaced_logging
+
+# Main thread setup
+var logService = initLogService()
+logService.addAppender(initConsoleLogAppender())
+
+var localLogSvc = threadLocalRef(logService) # for use on main thread
+
+# Worker thread function
+proc worker(ls: LogService) {.thread.} =
+  let localLogSvc = threadLocalRef(ls)
+  let logger = localLogSvc.getLogger("worker")
+
+  # Runtime configuration changes
+  localLogSvc.setThreshold("worker", lvlDebug)
+  logger.debug("Worker configured")
+
+# Safe thread creation
+createThread(workerThread, worker, logService)
+```
+
+### Dynamic Configuration
+```nim
+# Configuration can change at runtime
+proc configureLogging(localLogSvc: ThreadLocalLogService, verbose: bool) =
+  if verbose:
+    localLogSvc.setRootThreshold(lvlDebug)
+    localLogSvc.addAppender(initFileLogAppender("debug.log"))
+  else:
+    localLogSvc.setRootThreshold(lvlInfo)
+
+# Changes automatically propagate to all threads
 ```
 
 ## Loggers and Appenders
@@ -43,140 +86,383 @@ threshold, which determines which log events are acted upon by the appender,
 and, optionally, a namespace filter, which determines from which loggers the
 appender accepts log events.
 
-### Heirarchical Logging and Namespaces
+### Heirarchical Logging Namespaces
 
 Loggers are organized hierarchically, with the hierarchy defined by the logger
-name. A logger with the name `app/service/example` is a child of the logger
+scope. A logger with the scope `app/service/example` is conceptually a child of
-with the name `app/service`. By default, appenders accept log events from all
+the logger with the scope `app/service`. By default, appenders accept log
-loggers, but this can be restricted by setting a namespace filter on the
+events from all loggers, but this can be restricted by setting a namespace
-appender. An appender with a namespace set will accept log events from all
+filter on the appender. An appender with a namespace set will accept log events
-loggers with names that start with the namespace. For example, an appender with
+from all loggers with scopes that start with the namespace. For example, an
-the namespace `app` will accept log events from the loggers `app`,
+appender with the namespace `app` will accept log events from the loggers
-`app/service`, and `app/service/example`, but not from `api/service`.
+`app`, `app/service`, and `app/service/example`, but not from `api/service`.
 
 The other impact of the logger heirarchy is in the effective logging level of
-the logger. Any logger can have an explicit logging level set, but if it does
+the logger. An explicit logging level threshold can be set for any scope. Any
-not, the effective logging level is inherited from ancestor loggers upwards in
+scope that does not have an explicit inherits its threshold from ancestor
-the logger heirarchy. This pattern is explained in detail in the [logback
+loggers upwards in the scope naming heirarchy. This pattern is explained in
-documentation][effective logging level] and applies in the same manner to
+detail in the [logback documentation][effective logging level] and applies in
-loggers in this library.
+the same manner to loggers in this library.
+
+### LogMessageFormater
+
+Both the [ConsoleLogAppender](#ConsoleLogAppender) and
+[FileLogAppender](#FileLogAppender) can be given a *LogMessageFormatter* to
+determine how a log message is formatted before being written.
+
+```nim
+type LogMessageFormatter* = proc (msg: LogMessage): string {.gcsafe.}
+```
+
+## Available Appenders
+
+### ConsoleLogAppender
+
+Used for writing logs to stdout or stderr.
+
+```nim
+proc initConsoleLogAppender*(
+    formatter = formatSimpleTextLog,
+      ## formatJsonStructuredLog is another useful formatter provided
+      ## or you can write your own
+    useStderr = false,  ## stdout is used by default
+    namespace = "",     ## appender matches all scopes by default
+    threshold = lvlAll  ## and accepts all message levels by default
+  ): ConsoleLogAppender {.gcsafe.}
+```
+
+The first time a message is sent to any *ConsoleLogAppender*, we create a
+writer thread which writes messages to the specified output in the order they
+are received, flushing the file handle after each write to enforce an ordering.
+The ConsoleLogAppender implementation uses a channel to send messages to the
+writer thread.
+
+### FileLogAppender
+
+Used for writing logs to files.
+
+```nim
+proc initFileLogAppender*(
+    filePath: string,
+    formatter = formatSimpleTextLog,
+      ## formatJsonStructuredLog is another useful formatter provided
+      ## or you can write your own
+    namespace = "",
+    threshold = lvlAll
+  ): FileLogAppender {.gcsafe.}
+
+```
+
+Similar to the *ConsoleLogAppender* implementation, the first time a message is
+sent to any *FileLogAppender* we create a writer thread which writes messages
+to files associated with the *FileLogAppender* configured for the current
+*LogService*.
+
+`namespaced_logging` does not currently have built-in logic for file
+rotation, but it does play nice with external file rotation strategies. We do
+not hold open file handles. The *FileLogAppender* attempts to batch messages
+by destination file, opens the file with mode `fmAppend`, writes the current
+batch of log messages, and then closes the file handle. Because of this, it has
+no problem if another process moves or truncates any of the target log files.
+
+### StdLoggingAppender
+
+Provides a fallback to [std/logging][std-logging]-based logging. This is
+primarily intended for use in libraries or other contexts where you want to
+fall back to std/logging if the application is not using or hasn't configured
+namespaced\_logging.
+
+By default the *StdLoggingAppender* only logs when no namespaced\_logging
+appenders are configured but it can also be configured to always forward log
+messages regardless of whether namespaced\_logging has other appenders by
+setting `fallbackOnly = false`.
+
+```nim
+func initStdLoggingAppender*(
+    fallbackOnly = true,
+    formatter = formatForwardedLog,
+    namespace = "",
+    threshold = lvlAll): StdLoggingAppender {.gcsafe.}
+```
+
+### CustomLogAppender
+
+Provides an extension point for custom logging implementations.
+
+```nim
+func initCustomLogAppender*[T](
+    state: T,   # arbitrary state needed for the appender
+    doLogMessage: CustomLogAppenderFunc[T],
+      # custom log appender implementation
+    namespace = "",
+    threshold = lvlAll): CustomLogAppender[T] {.gcsafe.} =
+```
+
+The `state` field allows you to explicitly pass in any data that is required
+for the custom functionality.
+
+*TODO: rethink this. I chose this to avoid GC-safety issues copying closures
+across threads, but maybe I don't need this separate, explicit state field.*
+
+> [!CAUTION] The `state` data type must support copy semantics on assignment.
+> It is possible to pass a `ref` to `state` and/or data structures that include
+> `ref`s, but **you must guarantee they remain valid**, either by allocating
+> shared memeory, or (preferably) keeping alive a reference to them that the GC
+> is aware of, either on the thread where they were initialized or by
+> explicitly telling the GC about the cross-thread reference *(TODO: how?)*.
+
+See [testutil][] and the unit tests in [namespaced\_logging][nsl-unit-tests]
+for an example.
 
 
 ## Notes on Use in Multi-Threaded Applications
 
-The loggers and appenders in this library are thread-safe and behaves more
+The loggers and appenders in this library are thread-safe and are intended to
-intuitively in a multi-threaded environment than `std/logging`, particularly in
+behave more intuitively in a multi-threaded environment than
-environments where the logging setup code may be separated from the
+[std/logging][std-logging] while presenting a similar API. This is particularly
+true in environments where the logging setup code may be separated from the
 thread-management code (in an HTTP server, for example).
 
 The *LogService* object is the main entry point for the logging system and
-should be initialized on the main thread. The *LogService* contains the "source
+should be initialized on the main thread. The *LogService* contains a reference
-of truth" for logging configuration and is shared between all threads.
+to the "source of truth" for logging configuration and is safe to be shared
-Internally all access to the *LogService* is protected by a mutex.
+between all threads.
 
-Logging can be very noisy and if the *LogService* needed to be consulted for
+The thread which initializes a *LogService* must also be the longest-living
-every log event, it could easily become a performance bottleneck. To avoid
+thread that uses that *LogService* instance. If the initializing thread
-this, the *getLogger* procedure makes a thread-local copy of the logging system
+terminates or the *LogService* object in that thread goes out of scope while
-configuration (loggers defined and appenders attached).
+other threads are still running and using the *LogService*, the global state
+may be harvested by the garbage collector, leading to use-after-free errors
+when other threads attempt to log (likely causing segfaults).
 
-**Note** that this means that the thread-local cache of the logging system
+Individual threads should use the *threadLocalRef* proc to obtain a
-configuration can become stale if the logging system configuration is changed
+*ThreadLocalLogService* reference that can be used to create *Logger* objects.
-after the thread-local copy is made (if another appender is added, for
+*ThreadLocalLogService* objects cache the global *LogService* state locally to
-example). This is a trade-off to avoid the performance penalty of consulting
+avoid expensive locks on the shared state. Instead an atomic configuration
-the *LogService* for every log event.
+version number is maintained to allow the thread-local state to detect global
+configuration changes via an inexpensive [load][atomic-load] call and
+automatically synchronize only when necessary.
 
 This thread-local caching mechanism is the primary advantage of this logging
-system over `std/logging` in a multi-threaded environment as it means that
+system over std/logging in a multi-threaded environment as it means that
 the logging system itself is responsible for making sure appenders are
 configured for every thread where loggers are used, even if the thread
 initialization context is separated from the logging setup code.
 
-If you find yourself needing to change the logging configuration after the
-logging system has been initialized, the *reloadThreadState* procedure can be
-used to update the thread-local cache of the logging system configuration, but
-it must be called on the thread you wish to update.
 
-As a final note, the advice to initialize the *LogService* on the main thread
+## Architectural Design
-is primarily to simplify the configuration of the logging service and avoid the
-need to manually reload caches on individual threads. A *LogService* reference
-is required to call *getLogger*, but it can be created on any thread.
 
-## Custom Appender Implementations
+### Overview
 
-Due to the thread-safety of the logging system, there are a few additional
+The namespaced logging library attempts to balance performance, safety, and
-considerations when implementing custom appenders. The *LogAppender* abstract
+usability in multithreaded environments. The design centers on two key types:
-class is the base class for all appenders. To implement a custom appender, two
+*LogService* and *ThreadLocalLogService*.
-methods must be implemented:
-
-### `appendLogMessage`
 
+#### LogService (Value Type)
 ```nim
-method appendLogMessage*(appender: CustomLogAppender, msg: LogMessage): void {.base, gcsafe.}
+type LogService* = object
+  configVersion: int
+  global: GlobalLogService
+  appenders: seq[LogAppender]
+  thresholds: TableRef[string, Level]
 ```
 
-This is the primary appender implementation that takes a LogMessage and
+The *LogService* object is intended to support uses cases such as:
-writes it to the appender's destination. As the signature suggests, the
+- **Main thread initialization**: a mutable *LogService* supports all of the
-implementation must be GC-safe. As a multi-method, the *CustomLogAppender* type
+  configuration functions you would typically need when initializing logging
-should be replaced by the actual name of your custom appender.
+  for an application on the main thread.
+- **Cross-thread communication**: Being an `object` type, *LogService* follows
+  value semantics and can be safely copied between threads.
+- **Service composition**: independently initialized *LogService* objects are
+  truly independent and multiple can be created and embedded in larger
+  application contexts.
 
-Because the *LogAppender* uses multi-methods for dynamic dispatch, the
+> [!TIP]
-custom appender class must also be a `ref` type.
+> The *LogService* object is the object that is intended to be shared across
-
+> threads.
-### `initThreadCopy`
 
+#### ThreadLocalLogService (Reference Type)
 ```nim
-method initThreadCopy*(app: LogAppender): LogAppender {.base, gcsafe.}
+type ThreadLocalLogService* = ref LogService
 ```
 
-This method is used to create a thread-local copy of the appender. It is called
+*ThreadLocalLogService* is a reference to a thread-local copy of a *LogService*
-by the *reloadThreadState* procedure to update the thread-local cache of the
+and can be obtained via *threadLocalRef*. We purposefully use reference
-logging system configuration. The implementation will be passed the appender
+semantics within the context of a thread so that *Logger* objects created
-instance that was provided to the *addAppender* procedure and must return a
+within the same thread context share the same *ThreadLocalLogService*
-thread-local copy of that appender.
+reference, avoiding the need to synchronize every *Logger* individually.
 
-The `initThreadCopy` implementations for the built-in *ConsoleLogAppender* and
+*ThreadLocalLogService* is the object that users are expected to interact with
-*FileLogAppender* provide simple examples of how to implement this method by
+during regular operation and support both the configuration functions of
-simply copying state into the local thread, but this method can also be used
+*LogService* and the creation of *Logger* objects.
-to perform any other thread-specific initialization that may be required for
-the appender implementation.
 
-### Example Custom Appender
+> [!CAUTION]
+> *ThreadLocalLogService* objects should **never** be shared outside the
+> context of the thread in which they were initialized.
 
-The following defines a simple custom appender that writes log messages to a
+#### GlobalLogService (Internal)
-database table. It uses the [waterpark][] connection pooling library to manage
-database connections as waterpark is also thread-safe and makes implementation
-straight-forward.
 
+Under the hood *LogService* holds a reference to a *GlobalLogService*, a
+heap-allocated object that serves as the single source of truth for logging
+configuration. This internal type is not exposed to library users but manages:
+
+- **Shared configuration state**: Appenders, thresholds, and root logging level
+- **Synchronization primitives**: Locks and atomic variables for thread
+  coordination
+- **Background I/O threads**: Dedicated writer threads for console and file
+  output
+- **Configuration versioning**: Atomic version numbers for efficient change
+  detection
+
+The `GlobalLogService` ensures that configuration changes are safely propagated
+across all threads while maintaining high performance for logging operations.
+
+### Thread Safety Model
+
+#### Safe Cross-Thread Pattern
 ```nim
-import db_connectors/db_postgres
+# Main thread setup
-import namespaced_logging, waterpark, waterpark/db_postgres
+let logService = initLogService()
+logService.addAppender(initConsoleLogAppender())
 
-type DbLogAppender = ref object of LogAppender
+# Safe: value semantics allow crossing thread boundaries
-  dbPool: PostgresPool
+proc workerThread(ls: LogService) {.thread.} =
+  # Convert to thread-local reference for efficient operations
+  let tlls = threadLocalRef(ls)
+  let logger = tlls.getLogger("worker")
+  logger.info("Worker thread started")
 
-let dbPool: PostgresPool = newPostgresPool(10, "", "", "", connectionString)
+createThread(worker, workerThread, logService)
-
-method initThreadCopy*(app: LogAppender): LogAppender =
-  result = DbLogAppender(dbPool: dbPool) # copy semantics as PostgresPool is an object
-
-method appendLogMessage*(appender: DbLogAppender, msg: LogMessage): void {gcsafe.} =
-  appender.withConnection conn:
-    conn.insert(
-      "INSERT INTO log_events " &
-      "  (level, scope, message, error, timestamp, custom_fields) " &
-      "VALUES " &
-      "  (?, ?, ?, ?, ?, ?)",
-      msg.level,
-      msg.scope,
-      msg.message,
-      if msg.error.isSome: msg.error.msg
-      else: "",
-      msg.timestamp,
-      msg.additionalData)
 ```
 
+#### Unsafe Pattern (Avoided by Design)
+```nim
+# DON'T DO THIS - unsafe reference sharing
+# ThreadLocalLogService should not be shared across threads
+let tlls = threadLocalRef(initLogService())
+createThread(worker, someProc, tlls)  # ❌ Potential GC issues
+```
 
+### Configuration Synchronization
+
+#### Atomic Version Checking
+
+The library uses atomic version numbers to efficiently detect configuration
+changes:
+
+```nim
+proc ensureFreshness*(ls: var LogService) =
+  # Cheap atomic check first
+  if ls.configVersion == ls.global.configVersion.load():
+    return  # No changes, return immediately
+
+  # Only acquire lock and copy if versions differ
+  withLock ls.global.lock:
+    ls.configVersion = ls.global.configVersion.load
+    # Sync state...
+```
+
+Goals/Motivation:
+- Most logging operations skip expensive synchronization so the hot path is
+  fast.
+- Propogate changes automatically so all threads see configuration updates.
+- Minimize lock contention by only acquiring when configuration changes
+
+#### Thread-Local Caching
+
+Each thread maintains its own copy of the logging configuration in
+*ThreadLocalLogService*:
+
+- **Appenders**: Thread-local copies created via `clone()` method
+- **Thresholds**: Complete copy of namespace-to-level mappings
+- **Version tracking**: Local version number for change detection
+
+This caching strategy provides:
+- **High performance**: No locks needed for normal logging operations
+- **Consistency**: All threads eventually see the same configuration
+- **Isolation**: Thread-local state prevents cross-thread interference
+
+## Error Handling
+
+### Overview
+
+For errors that occur during logging operations, there is a callback-based
+error handling system designed to attempt to gracefully handle such failures.
+Since logging is typically a non-critical operation we prioritize application
+stability over guaranteed log delivery.
+
+### Error Handler
+
+The library uses a callback-based error handling pattern where applications can
+register custom error handlers to be notified when logging operations fail. The
+error handler receives:
+- `error`: The exception that caused the failure
+- `msg`: A descriptive message providing context about where the error occurred
+
+```nim
+type ErrorHandlerFunc* = proc(error: ref Exception, msg: string) {.gcsafe, nimcall.}
+```
+
+### Default Error Handler
+
+namespaced\_logging uses the `defaultErrorHandlerFunc` if a custom error
+handler has not been configured. The default handler:
+
+1. Attempts to write to stderr, assuming it is likely to be available and monitored
+2. Writes an error message and includes both the exception message and stack
+   trace (not available in release mode).
+3. Fails silently if it is unable to write to to stderr.
+
+### Configuration
+
+#### Setting Custom Error Handlers
+```nim
+# During initialization
+var logService = initLogService(errorHandler = myCustomErrorHandler)
+
+# Or at runtime on either the LogService...
+logService.setErrorHandler(myCustomErrorHandler)
+
+# ... or on a ThreadLocalLogService
+var localLogSvc = threadLocalRef(logService)
+localLogSvc.setErrorHandler(myCustomErrorHandler)
+```
+
+#### Disabling Error Reporting
+```nim
+proc silentErrorHandler(err: ref Exception, msg: string) {.gcsafe, nimcall.} =
+  discard # Do nothing
+
+logService.setErrorHandler(silentErrorHandler)
+```
+
+### Best Practices
+
+#### Provide Fallbacks
+
+```nim
+proc robustErrorHandler(err: ref Exception, msg: string) {.gcsafe, nimcall.} =
+  # Primary: Send to monitoring system
+  if not sendToMonitoring(err, msg):
+    # Secondary: Write to dedicated error log
+    if not writeToErrorLog(err, msg):
+      # Tertiary: Use stderr as last resort
+      try:
+        stderr.writeLine("LOGGING ERROR [" & msg & "]: " & err.msg)
+        stderr.flushFile()
+      except: discard
+```
+
+#### Keep Error Handlers Simple
+
+As much as possible, avoid complex operations that might themselves fail.
+Don't do heavy operations like database writes, complex network operations, or
+file system operations that might fail and cause cascading errors.
 
 [log4j]: https://logging.apache.org/log4j/2.x/
 [logback]: https://logback.qos.ch/
 [effective logging level]: https://logback.qos.ch/manual/architecture.html#effectiveLevel
+[atomic-load]: https://nim-lang.org/docs/atomics.html#load%2CAtomic%5BT%5D%2CMemoryOrder
+[std-logging]: https://nim-lang.org/docs/logging.html
+[testutil]: /blob/main/src/namespaced_logging/testutil.nim
+[nsl-unit-tests]: https://github.com/jdbernard/nim-namespaced-logging/blob/main/src/namespaced_logging.nim#L904

namespaced_logging.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version       = "2.0.0"
+version       = "2.0.2"
 author        = "Jonathan Bernard"
 description   = "Wrapper around std/logging to provide namespaced logging."
 license       = "MIT"
@@ -13,3 +13,7 @@ requires @["nim >= 2.2.0", "zero_functional"]
 
 # from https://git.jdb-software.com/jdb/nim-packages
 requires "timeutils"
+
+task test, "Run unittests for the package.":
+  exec "nimble c src/namespaced_logging.nim"
+  exec "src/namespaced_logging.out"

src/namespaced_logging.nim

@@ -1,9 +1,10 @@
-import std/[algorithm, atomics, json, locks, options, os, paths, sequtils,
+import std/[algorithm, atomics, exitprocs, json, locks, options, os, paths,
-            strutils, tables, times]
+            sequtils, strutils, tables, times]
 import timeutils
+import std/logging as stdlog
 
-from logging import Level
+from std/logging import Level
-export logging.Level
+export Level
 
 type
   GlobalLogServiceObj {.acyclic.} = object
@@ -15,13 +16,9 @@ type
     thresholds: TableRef[string, Level]
     rootLevel: Atomic[Level]
 
-    console: ThreadedConsoleLoggingState
-    file: ThreadedFileLoggingState
-
     errorHandler: ErrorHandlerFunc
     errorHandlerLock: Lock
 
-
   GlobalLogService = ref GlobalLogServiceObj
 
 
@@ -41,7 +38,7 @@ type
   ThreadLocalLogService* = ref LogService
 
 
-  Logger* = object
+  Logger* = ref object
     scope*: string
     threadSvc: ThreadLocalLogService
 
@@ -87,18 +84,11 @@ type
     absPath: Path
 
 
-  ThreadedConsoleLoggingState = object
+  LogWriterThreadState[M] = object
     initialized: Atomic[bool]
     shutdown: Atomic[bool]
-    chan: Channel[ConsoleMessage]
+    chan: Channel[M]
-    writerThread: Thread[GlobalLogService]
+    writerThread: Thread[void]
-
-
-  ThreadedFileLoggingState = object
-    initialized: Atomic[bool]
-    shutdown: Atomic[bool]
-    chan: Channel[FileMessage]
-    writerThread: Thread[GlobalLogService]
 
 
   ConsoleLogAppender* = ref object of LogAppender
@@ -123,6 +113,61 @@ type
     formatter*: LogMessageFormatter
     absPath*: Path
 
+  StdLoggingAppender* = ref object of LogAppender
+    ## Log appender that forwards log messages to the std/logging
+    ## implementation. This is primarily intended for libraries and other
+    ## situations where you expect that your code will be third-party to others
+    ## and want to respect applications which use std/logging for log handlers
+    ## and configuration.
+
+    fallbackOnly*: bool
+      ## when true, only forward to std/logging where there are no appenders
+      ## configured on the related LogService
+
+    formatter*: LogMessageFormatter
+
+const UninitializedConfigVersion = low(int)
+let JNULL = newJNull()
+
+var consoleLogging {.global.}: LogWriterThreadState[ConsoleMessage]
+var fileLogging {.global.}: LogWriterThreadState[FileMessage]
+var loggingThreadInitLock {.global.}: Lock
+
+initLock(loggingThreadInitLock)
+
+
+proc initLogMessage*(
+    scope: string,
+    lvl: Level,
+    message: string,
+    error: Option[ref Exception] = none[ref Exception](),
+    additionalData: JsonNode = JNULL): LogMessage =
+
+  LogMessage(
+    scope: scope,
+    level: lvl,
+    error: error,
+    timestamp: now(),
+    message: message,
+    additionalData: additionalData)
+
+
+proc initLogMessage*(
+    scope: string,
+    lvl: Level,
+    msg: JsonNode,
+    error: Option[ref Exception] = none[ref Exception]()): LogMessage =
+
+  LogMessage(
+    scope: scope,
+    level: lvl,
+    error: error,
+    timestamp: now(),
+    message:
+      if msg.hasKey("message"): msg["message"].getStr
+      else: "",
+    additionalData: msg)
+
 
 method clone*(app: LogAppender): LogAppender {.base, gcsafe.} =
   raise newException(CatchableError, "missing concrete implementation")
@@ -144,40 +189,39 @@ proc defaultErrorHandlerFunc*(
     stderr.flushFile()
   except Exception: discard # we tried...
 
-proc shutdownThreadedConsoleLogging(gls: var GlobalLogServiceObj) =
+proc shutdownThreadedConsoleLogging() =
-  if not gls.console.initialized.load(): return
+  if not consoleLogging.initialized.load(): return
 
-  gls.console.shutdown.store(true) # signal shutdown
+  withLock loggingThreadInitLock:
+    consoleLogging.shutdown.store(true) # signal shutdown
 
-  # Send sentinel values to wake up the writer thread
+    # Send sentinel values to wake up the writer thread
-  try: gls.console.chan.send(ConsoleMessage(message: "", useStderr: false))
+    try: consoleLogging.chan.send(ConsoleMessage(message: "", useStderr: false))
-  except Exception: discard
+    except Exception: discard
 
-  joinThread(gls.console.writerThread)
+    joinThread(consoleLogging.writerThread)
-  gls.console.chan.close()
+    consoleLogging.chan.close()
-  gls.console.initialized.store(false)
+    consoleLogging.initialized.store(false)
 
 
-proc shutdownThreadedFileLogging(gls: var GlobalLogServiceObj) =
+proc shutdownThreadedFileLogging() =
-  if not gls.file.initialized.load(): return
+  if not fileLogging.initialized.load(): return
 
-  gls.file.shutdown.store(true) # signal shutdown
+  fileLogging.shutdown.store(true) # signal shutdown
 
-  try: gls.file.chan.send(FileMessage(message: "", absPath: Path("/")))
+  withLock loggingThreadInitLock:
-  except Exception: discard
+    try: fileLogging.chan.send(FileMessage(message: "", absPath: Path("/")))
+    except Exception: discard
 
-  joinThread(gls.file.writerThread)
+    joinThread(fileLogging.writerThread)
-  gls.file.chan.close()
+    fileLogging.chan.close()
-  gls.file.initialized.store(false)
+    fileLogging.initialized.store(false)
 
 
 proc `=destroy`*(gls: var GlobalLogServiceObj) =
   # only one thread should cleanup
   if not gls.initialized.exchange(false): return
 
-  gls.shutdownThreadedConsoleLogging()
-  gls.shutdownThreadedFileLogging()
-
   try: deinitLock(gls.lock)
   except Exception: discard
 
@@ -210,6 +254,28 @@ proc ensureFreshness*(ls: var LogService) =
 proc ensureFreshness*(ls: ThreadLocalLogService) = ensureFreshness(ls[])
 
 
+proc initGlobalLogService(
+    rootLevel = lvlAll,
+    errorHandler = defaultErrorHandlerFunc): GlobalLogService =
+  result = GlobalLogService()
+  result.configVersion.store(0)
+  initLock(result.lock)
+  initLock(result.errorHandlerLock)
+
+  result.appenders = @[]
+  result.thresholds = newTable[string, Level]()
+  result.rootLevel.store(rootLevel)
+  result.errorHandler = errorHandler
+
+  result.initialized.store(true)
+
+proc initLogService(gls: GlobalLogService): LogService =
+  var lsRef: ThreadLocalLogService = ThreadLocalLogService(
+    configVersion: UninitializedConfigVersion, global: gls)
+  ensureFreshness(lsRef)
+  result = lsRef[]
+
+
 proc initLogService*(
     rootLevel = lvlAll,
     errorHandler = defaultErrorHandlerFunc): LogService =
@@ -227,24 +293,12 @@ proc initLogService*(
   ## configure thresholds, and create loggers. The ref returned by this
   ## procedure should also be retained by the main thread so that garbage
   ## collection does not harvest the global state while it is still in use.
-  let global = GlobalLogService()
+  let global = initGlobalLogService(rootLevel, errorHandler)
-  global.configVersion.store(0)
+  result = initLogService(global)
-  global.initialized.store(true)
-  initLock(global.lock)
-  initLock(global.errorHandlerLock)
-
-  global.appenders = @[]
-  global.thresholds = newTable[string, Level]()
-  global.rootLevel.store(rootLevel)
-  global.errorHandler = errorHandler
-
-  var lsRef: ThreadLocalLogService = ThreadLocalLogService(configVersion: -1, global: global)
-  ensureFreshness(lsRef)
-  result = lsRef[]
 
 
 proc threadLocalRef*(ls: LogService): ThreadLocalLogService =
-  result = new(LogService)
+  new result
   result[] = ls
 
 
@@ -362,6 +416,15 @@ proc getLogger*(
   result = Logger(scope: scope, threadSvc: ls)
 
 
+proc getLogger*(
+    ls: Option[ThreadLocalLogService],
+    scope: string,
+    lvl: Option[Level] = none[Level]()): Option[Logger] {.gcsafe.} =
+  return
+    if ls.isSome: some(getLogger(ls.get, scope, lvl))
+    else: none[Logger]()
+
+
 proc addAppender*(ls: var LogService, appender: LogAppender) {.gcsafe.} =
   ## Add a log appender to the global log service and refresh the local thread
   ## state. The updated global state will trigger other threads to refresh
@@ -378,6 +441,19 @@ proc addAppender*(ls: ThreadLocalLogService, appender: LogAppender) {.gcsafe.} =
   addAppender(ls[], appender)
 
 
+proc clearAppenders*(ls: var LogService) {.gcsafe.} =
+  ## Remove all log appenders added to the global log service and refresh the
+  ## local thread state. The updated global state will trigger other threads to
+  ## refresh their state as well.
+  withLock ls.global.lock:
+    ls.global.appenders = @[]
+    ls.global.configVersion.atomicInc
+
+
+proc clearAppenders*(ls: ThreadLocalLogService) {.gcsafe.} =
+  clearAppenders(ls[])
+
+
 func getEffectiveThreshold(logger: Logger): Level {.gcsafe.} =
   ## Get the effective logging level threshold for a logger. This is the most
   ## specific level that is set for the logger or any of its parents. The root
@@ -399,89 +475,173 @@ func getEffectiveThreshold(logger: Logger): Level {.gcsafe.} =
     result = logger.threadSvc.thresholds[namespaces[0]]
 
 
-proc doLog(logger: Logger, msg: LogMessage) {.gcsafe.} =
+proc isEnabled*(l: Logger, lvl: Level): bool {.inline,gcsafe.} =
-  ensureFreshness(logger.threadSvc)
+  lvl >= l.getEffectiveThreshold
 
-  if msg.level < logger.getEffectiveThreshold: return
 
+proc sendToAppenders(logger: Logger, msg: LogMessage) {.gcsafe,inline.} =
   for app in logger.threadSvc.appenders:
     if logger.scope.startsWith(app.namespace) and msg.level >= app.threshold:
       app.appendLogMessage(logger.threadSvc, msg)
 
 
-proc log*(l: Logger, lvl: Level, msg: string) {.gcsafe.} =
+template log*(l: Logger, lm: LogMessage) =
-  l.doLog(LogMessage(
+  ensureFreshness(l.threadSvc)
-    scope: l.scope,
+
-    level: lvl,
+  if lm.level >= l.getEffectiveThreshold:
-    error: none[ref Exception](),
+    sendToAppenders(l, lm)
-    timestamp: now(),
+
-    message: msg,
+template log*(l: Logger, lvl: Level, msg: untyped) =
-    additionalData: newJNull()))
+  ensureFreshness(l.threadSvc)
+
+  if lvl >= l.getEffectiveThreshold:
+    sendToAppenders(l, initLogMessage(l.scope, lvl, msg))
 
 
-proc log*(
+template log*[T: ref Exception](l: Logger, lvl: Level, err: T, msg: untyped) =
-    l: Logger,
+  ensureFreshness(l.threadSvc)
+
+  if lvl >= l.getEffectiveThreshold:
+    sendToAppenders(
+      l,
+      initLogMessage(l.scope, lvl, msg, some(cast[ref Exception](err))))
+
+template log*(l: Option[Logger], lm: LogMessage) =
+  if l.isSome: log(l.get, lm)
+
+template log*(l: Option[Logger], lvl: Level, msg: untyped) =
+  if l.isSome: log(l.get, lvl, msg)
+
+template log*(
+    l: Option[Logger],
     lvl: Level,
     error: ref Exception,
-    msg: string ) {.gcsafe.} =
+    msg: untyped) =
-  l.doLog(LogMessage(
-    scope: l.scope,
-    level: lvl,
-    error: some(error),
-    timestamp: now(),
-    message: msg,
-    additionalData: newJNull()))
-
-
-proc log*(l: Logger, lvl: Level, msg: JsonNode) {.gcsafe.} =
-  l.doLog(LogMessage(
-    scope: l.scope,
-    level: lvl,
-    error: none[ref Exception](),
-    timestamp: now(),
-    message:
-      if msg.hasKey("msg"): msg["msg"].getStr
-      else: "",
-    additionalData: msg))
-
-
-proc log*(l: Option[Logger], lvl: Level, msg: string) {.gcsafe.} =
-  if l.isSome: log(l.get, lvl, msg)
-
-proc log*(l: Option[Logger], lvl: Level, msg: JsonNode) {.gcsafe.} =
-  if l.isSome: log(l.get, lvl, msg)
-
-proc log*(l: Option[Logger], lvl: Level, error: ref Exception, msg: string) {.gcsafe.} =
   if l.isSome: log(l.get, lvl, error, msg)
 
-template debug*[T](l: Logger, msg: T) = log(l, lvlDebug, msg)
+template debug*[L: Logger or Option[Logger], M](l: L, msg: M) =
-template info*[T](l: Logger, msg: T) = log(l, lvlInfo, msg)
+  log(l, lvlDebug, msg)
-template notice*[T](l: Logger, msg: T) = log(l, lvlNotice, msg)
-template warn*[T](l: Logger, msg: T) = log(l, lvlWarn, msg)
 
-template error*[T](l: Logger, msg: T) = log(l, lvlError, msg)
+template info*[L: Logger or Option[Logger], M](l: L, msg: M) =
-template error*(l: Logger, error: ref Exception, msg: string) =
+  log(l, lvlInfo, msg)
+
+template notice*[L: Logger or Option[Logger], M](l: L, msg: M) =
+  log(l, lvlNotice, msg)
+
+template warn*[L: Logger or Option[Logger], M](l: L, msg: M) =
+  log(l, lvlWarn, msg)
+
+template error*[L: Logger or Option[Logger], M](l: L, msg: M) =
+  log(l, lvlError, msg)
+
+template error*[L: Logger or Option[Logger], M](l: L, error: ref Exception, msg: M) =
   log(l, lvlError, error, msg)
 
-template fatal*[T](l: Logger, msg: T) = log(l, lvlFatal, msg)
+template fatal*[L: Logger or Option[Logger], M](l: L, msg: M) =
-template fatal*(l: Logger, error: ref Exception, msg: string) =
+  log(l, lvlFatal, msg)
+
+template fatal*[L: Logger or Option[Logger], M](l: L, error: ref Exception, msg: M) =
   log(l, lvlFatal, error, msg)
 
-template debug*[T](l: Option[Logger], msg: T) = log(l, lvlDebug, msg)
-template info*[T](l: Option[Logger], msg: T) = log(l, lvlInfo, msg)
-template notice*[T](l: Option[Logger], msg: T) = log(l, lvlNotice, msg)
-template warn*[T](l: Option[Logger], msg: T) = log(l, lvlWarn, msg)
-
-template error*[T](l: Option[Logger], msg: T) = log(l, lvlError, msg)
-template error*(l: Option[Logger], error: ref Exception, msg: string) =
-  log(l, lvlError, error, msg)
-
-template fatal*[T](l: Option[Logger], msg: T) = log(l, lvlFatal, msg)
-template fatal*(l: Option[Logger], error: ref Exception, msg: string) =
-  log(l, lvlFatal, error, msg)
 
 # -----------------------------------------------------------------------------
-# CustomerLogAppender Implementation
+# Writer Thread Implementations
+# -----------------------------------------------------------------------------
+
+proc consoleWriterLoop() {.thread.} =
+  while not consoleLogging.shutdown.load():
+    var didSomething = false
+
+    let (hasData, msg) = consoleLogging.chan.tryRecv()
+    if hasData and msg.message.len > 0:  # Skip empty sentinel messages
+      try:
+        let output =
+          if msg.useStderr: stderr
+          else: stdout
+        output.write(msg.message)
+        output.flushFile()
+        didSomething = true
+      except IOError:
+        discard
+
+    # Small delay if no work to prevent busy waiting
+    if not didSomething: sleep(100)
+
+
+proc fileWriterLoop() {.thread.} =
+  const bufLen = 128
+  var msgsByPath = newTable[Path, seq[FileMessage]]()
+
+  while not fileLogging.shutdown.load():
+    var didSomething = false
+
+    var msgBuf: array[bufLen, FileMessage]
+    var recvIdx = 0
+    var writeIdx = 0
+    var dataAvailable = true
+
+    while dataAvailable and recvIdx < bufLen:
+      # Fill our message buffer if we can
+      (dataAvailable, msgBuf[recvIdx]) = fileLogging.chan.tryRecv()
+      if dataAvailable: inc recvIdx
+
+    # Organize messages by destination file
+    msgsByPath.clear()
+    while writeIdx < recvIdx:
+      let msg = msgBuf[writeIdx]
+      inc writeIdx
+
+      if msg.message.len > 0:  # skip empty sentinel messages
+        if not msgsByPath.contains(msg.absPath): msgsByPath[msg.absPath] = @[]
+        msgsByPath[msg.absPath].add(msg)
+        didSomething = true
+
+    # Write all messages in file order to optimize file open/flush/close
+    for path, msgs in pairs(msgsByPath):
+      var f: File
+
+      if not open(f, $path, fmAppend):
+        # TODO: can we do better than silently failing here?
+        continue
+
+      for m in msgs:
+        try: writeLine(f, m.message)
+        except Exception: discard
+      flushFile(f)
+      close(f)
+
+    # Wait a bit if we had no work to prevent busy waiting
+    if not didSomething: sleep(100)
+
+
+proc initThreadedConsoleLogging() =
+  if consoleLogging.initialized.load: return
+
+  withLock loggingThreadInitLock:
+    if consoleLogging.initialized.load: return
+    consoleLogging.chan.open()
+    consoleLogging.shutdown.store(false)
+
+    # Create writer thread with reference to the service
+    createThread(consoleLogging.writerThread, consoleWriterLoop)
+    consoleLogging.initialized.store(true)
+
+
+proc initThreadedFileLogging() =
+  if fileLogging.initialized.load: return
+
+  withLock loggingThreadInitLock:
+    if fileLogging.initialized.load: return
+    fileLogging.chan.open()
+    fileLogging.shutdown.store(false)
+
+    # Create writer thread with reference to the service
+    createThread(fileLogging.writerThread, fileWriterLoop)
+    fileLogging.initialized.store(true)
+
+
+# -----------------------------------------------------------------------------
+# CustomLogAppender Implementation
 # -----------------------------------------------------------------------------
 
 func initCustomLogAppender*[T](
@@ -491,7 +651,7 @@ func initCustomLogAppender*[T](
     threshold = lvlAll): CustomLogAppender[T] {.gcsafe.} =
 
   if doLogMessage.isNil:
-    debugEcho "initCustomLogAppender: doLogMessage is nil"
+    raise newException(ValueError, "initCustomLogAppender: doLogMessage is nil")
 
   result = CustomLogAppender[T](
     namespace: namespace,
@@ -500,8 +660,8 @@ func initCustomLogAppender*[T](
     state: state)
 
 method clone*[T](cla: CustomLogAppender[T]): LogAppender {.gcsafe.} =
-  if cla.doLogMessage.isNil:
+  assert not cla.doLogMessage.isNil,
-    debugEcho "CustomLogAppender#clone: source doLogMessage is nil"
+    "CustomLogAppender#clone: source doLogMessage is nil"
 
   result = CustomLogAppender[T](
     namespace: cla.namespace,
@@ -516,7 +676,7 @@ method appendLogMessage[T](
     msg: LogMessage) {.gcsafe.} =
   try:
     if cla.doLogMessage.isNil:
-      debugEcho "doLogMessage is nil"
+      raise newException(ValueError, "CustomLogAppender.appendLogMessage: doLogMessage is nil")
     else: cla.doLogMessage(cla.state, msg)
   except Exception:
     ls.global.reportLoggingError(
@@ -540,41 +700,6 @@ proc initConsoleLogAppender*(
     useStderr: useStderr)
 
 
-proc consoleWriterLoop(gls: GlobalLogService) {.thread.} =
-  while not gls.console.shutdown.load():
-    var didSomething = false
-
-    let (hasData, msg) = gls.console.chan.tryRecv()
-    if hasData and msg.message.len > 0:  # Skip empty sentinel messages
-      try:
-        let output =
-          if msg.useStderr: stderr
-          else: stdout
-        output.write(msg.message)
-        output.flushFile()
-        didSomething = true
-      except IOError:
-        discard
-
-    # Small delay if no work to prevent busy waiting
-    if not didSomething: sleep(100)
-
-
-proc initThreadedConsoleLogging(gls: GlobalLogService) =
-  if gls.console.initialized.load() or  # don't double-init
-     not gls.initialized.load():        # don't init if the gls is shutting down
-    return
-
-  withLock gls.lock:
-    if gls.console.initialized.load(): return
-    gls.console.chan.open()
-    gls.console.shutdown.store(false)
-
-    # Create writer thread with reference to the service
-    createThread(gls.console.writerThread, consoleWriterLoop, gls)
-    gls.console.initialized.store(true)
-
-
 method clone*(cla: ConsoleLogAppender): LogAppender {.gcsafe.} =
   result = ConsoleLogAppender(
     namespace: cla.namespace,
@@ -588,11 +713,11 @@ proc appendLogMessageMultiThreaded(
     ls: ref LogService,
     msg: LogMessage) {.gcsafe.} =
 
-  if not ls.global.console.initialized.load():
+  if not consoleLogging.initialized.load():
-    ls.global.initThreadedConsoleLogging()
+    initThreadedConsoleLogging()
 
   try:
-    ls.global.console.chan.send(ConsoleMessage(
+    consoleLogging.chan.send(ConsoleMessage(
       message: cla.formatter(msg),
       useStderr: cla.useStderr))
   except Exception:
@@ -659,67 +784,6 @@ proc initFileLogAppender*(
     formatter: formatter,
     absPath: absolutePath(Path(filePath)))
 
-  # TODO: initialize global state for the file log writer
-
-
-proc fileWriterLoop(gls: GlobalLogService) {.thread.} =
-  const bufLen = 128
-  var msgsByPath = newTable[Path, seq[FileMessage]]()
-
-  while not gls.file.shutdown.load():
-    var didSomething = false
-
-    var msgBuf: array[bufLen, FileMessage]
-    var recvIdx = 0
-    var writeIdx = 0
-    var dataAvailable = true
-
-    while dataAvailable and recvIdx < bufLen:
-      # Fill our message buffer if we can
-      (dataAvailable, msgBuf[recvIdx]) = gls.file.chan.tryRecv()
-      if dataAvailable: inc recvIdx
-
-    # Organize messages by destination file
-    msgsByPath.clear()
-    while writeIdx < recvIdx:
-      let msg = msgBuf[writeIdx]
-      inc writeIdx
-
-      if msg.message.len > 0:  # skip empty sentinel messages
-        if not msgsByPath.contains(msg.absPath): msgsByPath[msg.absPath] = @[]
-        msgsByPath[msg.absPath].add(msg)
-        didSomething = true
-
-    # Write all messages in file order to optimize file open/flush/close
-    for path, msgs in pairs(msgsByPath):
-      var f: File
-
-      if not open(f, $path, fmAppend):
-        # TODO: can we do better than silently failing here?
-        continue
-
-      for m in msgs:
-        try: writeLine(f, m.message)
-        except Exception: discard
-      flushFile(f)
-      close(f)
-
-    # Wait a bit if we had no work to prevent busy waiting
-    if not didSomething: sleep(100)
-
-
-proc initThreadedFileLogging(gls: GlobalLogService) =
-  if gls.file.initialized.load(): return
-
-  withLock gls.lock:
-    if gls.file.initialized.load(): return
-    gls.file.chan.open()
-    gls.file.shutdown.store(false)
-
-    # Create writer thread with reference to the service
-    createThread(gls.file.writerThread, fileWriterLoop, gls)
-    gls.file.initialized.store(true)
-
 
 method clone*(fla: FileLogAppender): LogAppender {.gcsafe.} =
   result = FileLogAppender(
@@ -734,11 +798,11 @@ proc appendLogMessageMultiThreaded(
     ls: ref LogService,
     msg: LogMessage) {.gcsafe.} =
 
-  if not ls.global.file.initialized.load():
+  if not fileLogging.initialized.load():
-    ls.global.initThreadedFileLogging()
+    initThreadedFileLogging()
 
   try:
-    ls.global.file.chan.send(FileMessage(
+    fileLogging.chan.send(FileMessage(
       message: fla.formatter(msg),
       absPath: fla.absPath))
   except Exception: discard
@@ -774,14 +838,66 @@ method appendLogMessage(
       "unable to append to FileLogAppender")
 
 
+# -----------------------------------------------------------------------------
+# StdLoggingAppender Implementation
+# -----------------------------------------------------------------------------
+
+func formatForwardedLog*(lm: LogMessage): string =
+  ## Default formatter for the StdLoggingAppender that prepends the logger
+  ## scope to the message before formatting the message via
+  ## *formatSimpleTextLog*
+  "[" & lm.scope & "] " & formatSimpleTextLog(lm)
+
+
+func initStdLoggingAppender*(
+    fallbackOnly = true,
+    formatter = formatForwardedLog,
+    namespace = "",
+    threshold = lvlAll): StdLoggingAppender {.gcsafe.} =
+
+  result = StdLoggingAppender(
+    namespace: namespace,
+    threshold: threshold,
+    fallbackOnly: fallbackOnly,
+    formatter: formatter)
+
+
+method clone*(sla: StdLoggingAppender): LogAppender {.gcsafe.} =
+  result = StdLoggingAppender(
+    namespace: sla.namespace,
+    threshold: sla.threshold,
+    fallbackOnly: sla.fallbackOnly,
+    formatter: sla.formatter)
+
+
+method appendLogMessage*(
+    sla: StdLoggingAppender,
+    ls: ThreadLocalLogService,
+    msg: LogMessage) {.gcsafe.} =
+
+  if sla.fallbackOnly and ls.appenders.len > 1: return
+
+  stdlog.log(msg.level, sla.formatter(msg))
+
+
+# -----------------------------------------------------------------------------
+# Cleanup
+# -----------------------------------------------------------------------------
+
+addExitProc(proc() =
+  shutdownThreadedConsoleLogging()
+  shutdownThreadedFileLogging()
+)
+
+
+# -----------------------------------------------------------------------------
+# Tests
+# -----------------------------------------------------------------------------
 
 when isMainModule:
 
-  import std/[tempfiles, unittest]
+  import std/[files, tempfiles, unittest]
   import ./namespaced_logging/testutil
-  # -----------------------------------------------------------------------------
-  # Tests
-  # -----------------------------------------------------------------------------
 
   suite "GlobalLogService Initialization":
 
@@ -905,8 +1021,7 @@ when isMainModule:
     setup:
       let ls = threadLocalRef(initLogService())
       let loggedMsgs = initLoggedMessages()
-      let testAppender = initTestLogAppender(loggedMsgs)
+      ls.addAppender(initTestLogAppender(loggedMsgs))
-      ls.addAppender(testAppender)
 
     test "getLogger creates logger with correct scope":
       let logger = ls.getLogger("api/users")
@@ -916,6 +1031,26 @@ when isMainModule:
       let logger = ls.getLogger("api/users", some(lvlWarn))
       check ls.thresholds["api/users"] == lvlWarn
 
+    test "log methods work":
+      let logger = ls.getLogger("test")
+
+      logger.log(lvlDebug, "debug string msg")
+      logger.log(lvlInfo, %*{"message": "info json msg"})
+      logger.log(lvlNotice, "notice string msg")
+      logger.log(lvlError, newException(ValueError, "exception msg"), "error ex. msg")
+
+      let lm = loggedMsgs.get()
+      check:
+        lm.len == 4
+        lm[0].level == lvlDebug
+        lm[0].message.contains("debug string msg")
+        lm[1].level == lvlInfo
+        lm[1].message.contains("info json msg")
+        lm[2].level == lvlNotice
+        lm[2].message.contains("notice string msg")
+        lm[3].level == lvlError
+        lm[3].message.contains("error ex. msg")
+
     test "logger convenience methods work":
       let logger = ls.getLogger("test")
 
@@ -964,8 +1099,7 @@ when isMainModule:
     setup:
       let ls = threadLocalRef(initLogService())
       let loggedMsgs = initLoggedMessages()
-      let testAppender = initTestLogAppender(loggedMsgs)
+      ls.addAppender(initTestLogAppender(loggedMsgs))
-      ls.addAppender(testAppender)
 
     test "root level filtering":
       ls.setRootThreshold(lvlInfo)
@@ -1015,6 +1149,25 @@ when isMainModule:
         lm[0].scope == "api/users/detail"
         lm[0].level == lvlDebug
 
+    test "message construction is avoided if the message is not logged":
+
+      var expensiveCallCount = 0
+      proc expensiveCall(): int =
+        inc expensiveCallCount
+        return expensiveCallCount
+
+      ls.setThreshold("test", lvlInfo)
+      let logger = ls.getLogger("test")
+
+      logger.debug("Expensive call (" & $expensiveCall() & ")")
+      logger.info("Expensive call (" & $expensiveCall() & ")")
+
+      let lm = loggedMsgs.get()
+      check:
+        lm.len == 1
+        lm[0].message.contains("Expensive call (1)")
+        expensiveCallCount == 1
+
   suite "Appender Functionality":
     setup:
       let ls = threadLocalRef(initLogService())
@@ -1113,6 +1266,8 @@ when isMainModule:
         lines.len == 1
         "test message" in lines[0]
 
+      removeFile(pathStr)
+
     test "file appender clone":
       let original = initFileLogAppender("tempfile.log", namespace = "test")
       let cloned = clone(original)
@@ -1121,3 +1276,107 @@ when isMainModule:
       let clonedFile = FileLogAppender(cloned)
       check clonedFile.absPath == original.absPath
       check clonedFile.namespace == "test"
+
+  suite "StdLoggingAppender":
+
+    var fileLogger: FileLogger
+    var tempFile: File
+    var tempFilename: string
+
+    setup:
+      let ls = threadLocalRef(initLogService())
+      (tempFile, tempFilename) = createTempFile("stdlog_test", ".tmp.log")
+      fileLogger = newFileLogger(tempFile, flushThreshold = lvlAll)
+      addHandler(fileLogger)
+
+    teardown:
+      removeHandler(fileLogger)
+      try: close(tempFile)
+      except Exception: discard
+      removeFile(tempFilename)
+
+    test "forwards to std logging":
+      ls.addAppender(initStdLoggingAppender())
+      let logger = ls.getLogger("test")
+
+      logger.debug("message at debug")
+      logger.info("message at info")
+      logger.error("message at error")
+
+      tempFile.flushFile()
+      close(tempFile)
+
+      check open(tempFile, tempFilename, fmRead)
+      let lines = toSeq(lines(tempFile))
+      check:
+        lines.len == 3
+        lines[0] == "DEBUG [test] message at debug"
+        lines[1] == "INFO [test] message at info"
+        lines[2] == "ERROR [test] message at error"
+
+    test "fallbackOnly works when on":
+      ls.addAppender(initStdLoggingAppender())
+      let logger = ls.getLogger("test")
+
+      logger.debug("message at debug")
+      logger.info("message at info")
+      logger.error("message at error")
+
+      let loggedMsgs = initLoggedMessages()
+      ls.addAppender(initTestLogAppender(loggedMsgs))
+
+      logger.notice("message at notice")
+      logger.warn("message at warn")
+      logger.fatal("message at fatal")
+
+      tempFile.flushFile()
+      close(tempFile)
+
+      check open(tempFile, tempFilename, fmRead)
+      let lines = toSeq(lines(tempFile))
+      let lm = loggedMsgs.get()
+      check:
+        lines.len == 3
+        lines[0] == "DEBUG [test] message at debug"
+        lines[1] == "INFO [test] message at info"
+        lines[2] == "ERROR [test] message at error"
+
+        lm.len == 3
+        lm[0].message.contains("message at notice")
+        lm[1].message.contains("message at warn")
+        lm[2].message.contains("message at fatal")
+
+    test "fallbackOnly works when off":
+      ls.addAppender(initStdLoggingAppender(fallbackOnly = false))
+      let logger = ls.getLogger("test")
+
+      logger.debug("message at debug")
+      logger.info("message at info")
+      logger.error("message at error")
+
+      let loggedMsgs = initLoggedMessages()
+      ls.addAppender(initTestLogAppender(loggedMsgs))
+
+      logger.notice("message at notice")
+      logger.warn("message at warn")
+      logger.fatal("message at fatal")
+
+      tempFile.flushFile()
+      close(tempFile)
+
+      check open(tempFile, tempFilename, fmRead)
+      let lines = toSeq(lines(tempFile))
+      let lm = loggedMsgs.get()
+      check:
+        lines.len == 6
+        lines[0] == "DEBUG [test] message at debug"
+        lines[1] == "INFO [test] message at info"
+        lines[2] == "ERROR [test] message at error"
+        lines[3] == "NOTICE [test] message at notice"
+        lines[4] == "WARN [test] message at warn"
+        lines[5] == "FATAL [test] message at fatal"
+
+        lm.len == 3
+        lm[0].message.contains("message at notice")
+        lm[1].message.contains("message at warn")
+        lm[2].message.contains("message at fatal")

src/namespaced_logging/autoconfigured.nim

@@ -1,98 +0,0 @@
-import std/[json, options]
-from logging import Level
-import ../namespaced_logging
-
-export
-  # Types
-  Level,
-  Logger,
-  LogAppender,
-  LogMessage,
-  ConsoleLogAppender,
-  CustomLogAppender,
-  CustomLogAppenderFunction,
-  FileLogAppender,
-
-  # Procs/Funcs
-  `%`,
-  initConsoleLogAppender,
-  initCustomLogAppender,
-  initFileLogAppender,
-  formatJsonStructuredLog
-
-var globalLogServiceRef: ThreadLocalLogService = new(LogService)
-globalLogServiceRef[] = initLogService()
-
-var threadLocalLogServiceRef {.threadvar.}: ThreadLocalLogService
-var defaultLogger {.threadvar.}: Option[Logger]
-
-
-proc getThreadLocalLogServiceRef(): ThreadLocalLogService {.inline.} =
-  if threadLocalLogServiceRef.isNil:
-    threadLocalLogServiceRef = new(LogService)
-    threadLocalLogServiceRef[] = globalLogServiceRef[]
-
-  return threadLocalLogServiceRef
-
-proc getDefaultLogger(): Logger {.inline.} =
-
-  if defaultLogger.isNone:
-    defaultLogger = some(getThreadLocalLogServiceRef().getLogger(""))
-
-  return defaultLogger.get
-
-
-proc useForAutoconfiguredLogging*(ls: LogService) =
-  globalLogServiceRef[] = ls
-
-
-proc setRootLoggingThreshold*(lvl: Level) =
-  setRootThreshold(getThreadLocalLogServiceRef(), lvl)
-
-
-proc setLoggingThreshold*(scope: string, lvl: Level) =
-  setThreshold(getThreadLocalLogServiceRef(), scope, lvl)
-
-
-proc addLogAppender*(appender: LogAppender) =
-  addAppender(getThreadLocalLogServiceRef(), appender)
-
-
-proc getLogger*(scope: string, lvl: Option[Level] = none[Level]()): Logger =
-  getLogger(getThreadLocalLogServiceRef(), scope, lvl)
-
-
-proc log*(lvl: Level, msg: string) = getDefaultLogger().log(lvl, msg)
-proc log*(lvl: Level, msg: JsonNode) = getDefaultLogger().log(lvl, msg)
-
-proc log*(lvl: Level, error: ref Exception, msg: string) =
-  getDefaultLogger().log(lvl, error, msg)
-
-template debug*[T](msg: T) = log(lvlDebug, msg)
-template info*[T](msg: T) = log(lvlInfo, msg)
-template notice*[T](msg: T) = log(lvlNotice, msg)
-template warn*[T](msg: T) = log(lvlWarn, msg)
-template error*[T](msg: T) = log(lvlError, msg)
-template error*(error: ref Exception, msg: string) = log(lvlError, error, msg)
-template fatal*[T](msg: T) = log(lvlFatal, msg)
-template fatal*(error: ref Exception, msg: string) = log(lvlFatal, error, msg)
-
-when isMainModule:
-  import std/unittest
-  import ./testutil
-
-  suite "Autoconfigured Logging":
-    setup:
-      globalLogServiceRef[] = initLogService()
-      let loggedMessages = initLoggedMessages()
-      let testAppender = initTestLogAppender(loggedMessages)
-
-    test "simple no-config logging":
-      addLogAppender(testAppender)
-      info("test message")
-
-      let lm = loggedMessages.get()
-      check:
-        lm.len == 1
-        lm[0].level == lvlInfo
-        lm[0].message == "test message"