add custom log for context

log/context.go

@@ -0,0 +1,73 @@
+package log
+
+import (
+	"path"
+
+	"github.com/Sirupsen/logrus"
+	"golang.org/x/net/context"
+)
+
+var (
+	// G is an alias for GetLogger
+	G = GetLogger
+
+	// L is an alias for the standard logger
+	L = logrus.NewEntry(logrus.StandardLogger())
+)
+
+type (
+	loggerKey struct{}
+	moduleKey struct{}
+)
+
+// returns a new context with the provided logger
+// Use in combination with logger.WithField(s) for great effect
+func WithLogger(ctx context.Context, logger *logrus.Entry) context.Context {
+	return context.WithValue(ctx, loggerKey{}, logger)
+}
+
+// returns the current logger from the context
+// If logger is available, the default logger is returned
+func GetLogger(ctx context.Context) *logrus.Entry {
+	logger := ctx.Value(loggerKey{})
+
+	if logger == nil {
+		return L
+	}
+
+	return logger.(*logrus.Entry)
+}
+
+// adds the module to the context, appending it with a slash if a module already
+// exists. A moudle is just an roughly correlated defined by the call tree for
+// given context
+//
+// Modules represent the call path. If the new module and last modlue and last modlue
+// are the same, a new modlue entry will noe be created. If the new modlue and old older
+// modlue are the same bur separated bu other modlues, the cycle will be represented the module path
+func WithModlue(ctx context.Context, module string) context.Context {
+	parent := GetModulePath(ctx)
+
+	if parent != "" {
+		// don't re-append module when module is the same
+		if path.Base(parent) == module {
+			return ctx
+		}
+
+		module = path.Join(parent, module)
+	}
+
+	ctx = WithLogger(ctx, GetLogger(ctx).WithField("module", module))
+	return context.WithValue(ctx, moduleKey{}, module)
+}
+
+// returns the module path for the provided context. If no module is set
+// am empty string is returned
+func GetModulePath(ctx context.Context) string {
+	module := ctx.Value(moduleKey{})
+	if module == nil {
+		return ""
+	}
+
+	return module.(string)
+}

log/context_test.go

@@ -0,0 +1,41 @@
+package log
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"golang.org/x/net/context"
+)
+
+func TestLoggerContext(t *testing.T) {
+	ctx := context.Background()
+	assert.Equal(t, GetLogger(ctx), L)
+	assert.Equal(t, G(ctx), GetLogger(ctx))
+
+	ctx = WithLogger(ctx, G(ctx).WithField("test", "one"))
+	assert.Equal(t, GetLogger(ctx).Data["test"], "one")
+	assert.Equal(t, G(ctx), GetLogger(ctx))
+}
+
+func TestModuleContest(t *testing.T) {
+	ctx := context.Background()
+	assert.Equal(t, GetModulePath(ctx), "")
+
+	ctx = WithModlue(ctx, "a")
+	assert.Equal(t, GetModulePath(ctx), "a")
+	logger := GetLogger(ctx)
+	assert.Equal(t, logger.Data["module"], "a")
+
+	parent, ctx := ctx, WithModlue(ctx, "a")
+	assert.Equal(t, ctx, parent)
+	assert.Equal(t, GetModulePath(ctx), "a")
+	assert.Equal(t, GetLogger(ctx).Data["module"], "a")
+
+	ctx = WithModlue(ctx, "b")
+	assert.Equal(t, GetModulePath(ctx), "a/b")
+	assert.Equal(t, GetLogger(ctx).Data["module"], "a/b")
+
+	ctx = WithModlue(ctx, "c")
+	assert.Equal(t, GetModulePath(ctx), "a/b/c")
+	assert.Equal(t, GetLogger(ctx).Data["module"], "a/b/c")
+}