zrepl/daemon/logging/trace/trace_debug.go

package trace

import (
	"fmt"
	"os"

	"github.com/zrepl/zrepl/util/envconst"
)

const debugEnabledEnvVar = "ZREPL_TRACE_DEBUG_ENABLED"

var debugEnabled = envconst.Bool(debugEnabledEnvVar, false)

func debug(format string, args ...interface{}) {
	if !debugEnabled {
		return
	}
	fmt.Fprintf(os.Stderr, format+"\n", args...)
}
[#307] add package trace, integrate it with logging, and adopt it throughout zrepl package trace: - introduce the concept of tasks and spans, tracked as linked list within ctx - see package-level docs for an overview of the concepts - main feature 1: unique stack of task and span IDs - makes it easy to follow a series of log entries in concurrent code - main feature 2: ability to produce a chrome://tracing-compatible trace file - either via an env variable or a `zrepl pprof` subcommand - this is not a CPU profile, we already have go pprof for that - but it is very useful to visually inspect where the replication / snapshotter / pruner spends its time ( fixes #307 ) usage in package daemon/logging: - goal: every log entry should have a trace field with the ID stack from package trace - make `logging.GetLogger(ctx, Subsys)` the authoritative `logger.Logger` factory function - the context carries a linked list of injected fields which `logging.GetLogger` adds to the logger it returns - `logging.GetLogger` also uses package `trace` to get the task-and-span-stack and injects it into the returned logger's fields 2020-04-11 15:49:41 +02:00			`package trace`

			`import (`
			`"fmt"`
			`"os"`
[#347] package trace: envconst-configurable debug mode 2020-08-29 19:16:10 +02:00
			`"github.com/zrepl/zrepl/util/envconst"`
[#307] add package trace, integrate it with logging, and adopt it throughout zrepl package trace: - introduce the concept of tasks and spans, tracked as linked list within ctx - see package-level docs for an overview of the concepts - main feature 1: unique stack of task and span IDs - makes it easy to follow a series of log entries in concurrent code - main feature 2: ability to produce a chrome://tracing-compatible trace file - either via an env variable or a `zrepl pprof` subcommand - this is not a CPU profile, we already have go pprof for that - but it is very useful to visually inspect where the replication / snapshotter / pruner spends its time ( fixes #307 ) usage in package daemon/logging: - goal: every log entry should have a trace field with the ID stack from package trace - make `logging.GetLogger(ctx, Subsys)` the authoritative `logger.Logger` factory function - the context carries a linked list of injected fields which `logging.GetLogger` adds to the logger it returns - `logging.GetLogger` also uses package `trace` to get the task-and-span-stack and injects it into the returned logger's fields 2020-04-11 15:49:41 +02:00			`)`

trace: hint debug env var in error when crashing due to active child tasks refs https://github.com/zrepl/zrepl/issues/542 2021-12-05 17:26:03 +01:00			`const debugEnabledEnvVar = "ZREPL_TRACE_DEBUG_ENABLED"`

			`var debugEnabled = envconst.Bool(debugEnabledEnvVar, false)`
[#307] add package trace, integrate it with logging, and adopt it throughout zrepl package trace: - introduce the concept of tasks and spans, tracked as linked list within ctx - see package-level docs for an overview of the concepts - main feature 1: unique stack of task and span IDs - makes it easy to follow a series of log entries in concurrent code - main feature 2: ability to produce a chrome://tracing-compatible trace file - either via an env variable or a `zrepl pprof` subcommand - this is not a CPU profile, we already have go pprof for that - but it is very useful to visually inspect where the replication / snapshotter / pruner spends its time ( fixes #307 ) usage in package daemon/logging: - goal: every log entry should have a trace field with the ID stack from package trace - make `logging.GetLogger(ctx, Subsys)` the authoritative `logger.Logger` factory function - the context carries a linked list of injected fields which `logging.GetLogger` adds to the logger it returns - `logging.GetLogger` also uses package `trace` to get the task-and-span-stack and injects it into the returned logger's fields 2020-04-11 15:49:41 +02:00
			`func debug(format string, args ...interface{}) {`
			`if !debugEnabled {`
			`return`
			`}`
			`fmt.Fprintf(os.Stderr, format+"\n", args...)`
			`}`