11 Commits

Author SHA1 Message Date
7e1671b26e Allow inclusion of Exceptions in warn convenience templates. 2025-07-18 10:26:15 -05:00
f0f0084cfd Changing our mind: message -> msg; timestamp -> ts; error -> err 2025-07-14 15:30:21 -05:00
bff544ab89 Add convenience methods for setting thresholds. 2025-07-12 13:22:17 -05:00
3178c50936 Remove autoconfigured (didn't work as implemented). 2025-07-11 17:38:04 -05:00
1b598fb445 README typo/correction. 2025-07-11 09:27:08 -05:00
101ac8d869 Bump version. 2025-07-07 21:47:58 -05:00
a4464c7275 Add README examples for autoconfigured use-cases. 2025-07-07 21:09:38 -05:00
49755fa2af Add more unit tests. 2025-07-07 17:02:45 -05:00
b2d43d1c6d StdLoggingAppender - forward logs to std/logging
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.
2025-07-07 16:34:04 -05:00
c22e7edd5d Move autoconfiguration implementation into the main module.
Autoconfiguration implementation really needs access to internal fields
and data structures to work properly.

Additionally introduces the concept of GlobalLogService takeover
internally, which allows existing LogService instances to become aware
of a new GlobalLogService. This is needed for
`useForAutoconfiguredLogging` to work as one would naturally expect,
where Loggers that may have already been created (explicitly or
implicitly) by library or third-party code are kept up to date when the
application explicitly configures logging.
2025-07-07 16:29:58 -05:00
269cc81c82 Rewrite the log procs for better performance.
Previously, log message parsing and construction were performed before
we checked if we were actually going to log anything (based on our
thresholds). This change moves the logic for both the LogMessage
construction, as well as any logic in the calling context (string
concatenation etc.) after the threshold check.

This is to enable use-cases like this:

    logger.debug("Something interesting happened\p    context: " &
        expensiveCallToConstructFullContext())

and not have to pay the performance penalty of the string concatenation
in production settings when debug logging is turned off.
2025-07-07 16:21:59 -05:00
5 changed files with 567 additions and 429 deletions

1
.gitignore vendored
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@@ -3,3 +3,4 @@ nimcache/
tests/tests
src/namespaced_logging.out
src/namespaced_logging/autoconfigured
.worktrees

114
README.md
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@@ -8,7 +8,7 @@ four main motivating features:
- Safe and straightforward to use in multi-threaded applications.
- Native support for structured logging.
- Simple, autoconfigured usage pattern reminiscent of the
[std/logging][std-logging] interface.
[std/logging][std-logging] interface (*not yet implemented*)
## Getting Started
@@ -21,38 +21,6 @@ nimble install https://github.com/jdbernard/nim-namespaced-logging
## Usage Patterns
### Simple, Autoconfigured Setup
```nim
import namespaced_logging/autoconfigured
# Zero configuration of the LogService required, appender/logger configuration
# is immediately available
addLogAppender(initConsoleLogAppender())
info("Application started")
# Set global threshold
setRootLoggingThreshold(lvlWarn)
# Namespaced loggers, thresholds, and appenders supported
addLogAppender(initFileLogAppender(
filePath = "/var/log/app_db.log",
formatter = formatJsonStructuredLog, # provided in namespaced_logging
namespace = "app/db",
threshold = lvlInfo))
# in DB code
let dbLogger = getLogger("app/db/queryplanner")
dbLogger.debug("Beginning query plan...")
# native support for structured logs (import std/json)
dbLogger.debug(%*{
"method": "parseParams",
"message": "unrecognized param type",
"invalidType": $params[idx].type,
"metadata": %(params.meta)
} )
```
### Manual Configuration
```nim
import namespaced_logging
@@ -72,34 +40,6 @@ let apiLogger = localLogSvc.getLogger("api")
let dbLogger = localLogSvc.getLogger("db")
```
### Autoconfigured Multithreaded Application
```nim
import namespaced_logging/autoconfigured
import mummy, mummy/routers
# Main thread setup
addLogAppender(initConsoleLogAppender())
proc createApiRouter*(apiCtx: ProbatemApiContext): Router =
# This will run on a separate thread, but the thread creation is managed by
# mummy, not us. Log functions still operate correctly and respect the
# configuration setup on the main thread
let logger = getLogger("api")
logger.trace(%*{ "method_entered": "createApiRouter" })
# API route setup...
logger.debug(%*{ "method": "createApiRouter", "routes": numRoutes })
let server = newServer(createApiRouter(), workerThreads = 4)
ctx.server.serve(Port(8080))
info("Serving MyApp v1.0.0 on port 8080")
setThreshold("api", lvlTrace) # will be picked up by loggers on worker threads
```
### Manual Multithreaded Application
```nim
import namespaced_logging
@@ -225,6 +165,26 @@ 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.
@@ -244,7 +204,7 @@ 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.*
> [!WARNING] The `state` data type must support copy semantics on assignment.
> [!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
@@ -263,26 +223,17 @@ behave more intuitively in a multi-threaded environment than
true in environments where the logging setup code may be separated from the
thread-management code (in an HTTP server, for example).
As described in the [Getting Started](#getting-started) section, you can use
the `namespaced_logging/autoconfigured` import to use a simplified interface
that more closely matches the contract of [std/logging][std-logging]. In this
case all thread and state management is done for you. The only limitation is
that you cannot create multiple global *LogService* instances. In practice this
is an uncommon need.
The *LogService* object is the main entry point for the logging system and
should be initialized on the main thread. The *LogService* contains a reference
to the "source of truth" for logging configuration and is safe to be shared
between all threads.
If you do need or want the flexibility to manage the state yourself, import
`namespaced_logging` directly. In this case, the thread which initialized
*LogService* must also be the longest-living thread that uses that *LogService*
instance. If the initializing thread terminates or the *LogService* object in
that thread goes out of scope while 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).
When managing the state yourself, the *LogService* object is the main entry
point for the logging system and should be initialized on the main thread. The
*LogService* contains a reference to the "source of truth" for logging
configuration and is safe to be shared between all threads.
The thread which initializes a *LogService* must also be the longest-living
thread that uses that *LogService* instance. If the initializing thread
terminates or the *LogService* object in that thread goes out of scope while
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).
Individual threads should use the *threadLocalRef* proc to obtain a
*ThreadLocalLogService* reference that can be used to create *Logger* objects.
@@ -488,6 +439,7 @@ logService.setErrorHandler(silentErrorHandler)
### Best Practices
#### Provide Fallbacks
```nim
proc robustErrorHandler(err: ref Exception, msg: string) {.gcsafe, nimcall.} =
# Primary: Send to monitoring system

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@@ -1,6 +1,6 @@
# Package
version = "1.1.0"
version = "2.1.1"
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"

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@@ -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"