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authorPéter Szilágyi <peterke@gmail.com>2017-02-21 23:26:05 +0800
committerPéter Szilágyi <peterke@gmail.com>2017-02-23 18:00:05 +0800
commit47af53f9aaf9aa7b12cd976eb150ccf3d64da6fd (patch)
tree106c4a6a3a8f393b647cca767810f4babb5684da /log/handler_glog.go
parent3f923f390268bc912ceb162cc4dd63dc44cc3869 (diff)
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log: implement a glog style pattern matching handler
Diffstat (limited to 'log/handler_glog.go')
-rw-r--r--log/handler_glog.go227
1 files changed, 227 insertions, 0 deletions
diff --git a/log/handler_glog.go b/log/handler_glog.go
new file mode 100644
index 000000000..f8b932fd1
--- /dev/null
+++ b/log/handler_glog.go
@@ -0,0 +1,227 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package log
+
+import (
+ "errors"
+ "fmt"
+ "regexp"
+ "runtime"
+ "strconv"
+ "strings"
+ "sync"
+ "sync/atomic"
+)
+
+// errVmoduleSyntax is returned when a user vmodule pattern is invalid.
+var errVmoduleSyntax = errors.New("expect comma-separated list of filename=N")
+
+// errTraceSyntax is returned when a user backtrace pattern is invalid.
+var errTraceSyntax = errors.New("expect file.go:234")
+
+// GlogHandler is a log handler that mimics the filtering features of Google's
+// glog logger: setting global log levels; overriding with callsite pattern
+// matches; and requesting backtraces at certain positions.
+type GlogHandler struct {
+ origin Handler // The origin handler this wraps
+
+ level uint32 // Current log level, atomically accessible
+ override uint32 // Flag whether overrides are used, atomically accessible
+ backtrace uint32 // Flag whether backtrace location is set
+
+ patterns []pattern // Current list of patterns to override with
+ siteCache map[uintptr]Lvl // Cache of callsite pattern evaluations
+ location string // file:line location where to do a stackdump at
+ lock sync.RWMutex // Lock protecting the override pattern list
+}
+
+// NewGlogHandler creates a new log handler with filtering functionality similar
+// to Google's glog logger. The returned handler implements Handler.
+func NewGlogHandler(h Handler) *GlogHandler {
+ return &GlogHandler{
+ origin: h,
+ }
+}
+
+// pattern contains a filter for the Vmodule option, holding a verbosity level
+// and a file pattern to match.
+type pattern struct {
+ pattern *regexp.Regexp
+ level Lvl
+}
+
+// Verbosity sets the glog verbosity ceiling. The verbosity of individual packages
+// and source files can be raised using Vmodule.
+func (h *GlogHandler) Verbosity(level Lvl) {
+ atomic.StoreUint32(&h.level, uint32(level))
+}
+
+// Vmodule sets the glog verbosity pattern.
+//
+// The syntax of the argument is a comma-separated list of pattern=N, where the
+// pattern is a literal file name or "glob" pattern matching and N is a V level.
+//
+// For instance:
+//
+// pattern="gopher.go=3"
+// sets the V level to 3 in all Go files named "gopher.go"
+//
+// pattern="foo=3"
+// sets V to 3 in all files of any packages whose import path ends in "foo"
+//
+// pattern="foo/*=3"
+// sets V to 3 in all files of any packages whose import path contains "foo"
+func (h *GlogHandler) Vmodule(ruleset string) error {
+ var filter []pattern
+ for _, rule := range strings.Split(ruleset, ",") {
+ // Empty strings such as from a trailing comma can be ignored
+ if len(rule) == 0 {
+ continue
+ }
+ // Ensure we have a pattern = level filter rule
+ parts := strings.Split(rule, "=")
+ if len(parts) != 2 {
+ return errVmoduleSyntax
+ }
+ parts[0] = strings.TrimSpace(parts[0])
+ parts[1] = strings.TrimSpace(parts[1])
+ if len(parts[0]) == 0 || len(parts[1]) == 0 {
+ return errVmoduleSyntax
+ }
+ // Parse the level and if correct, assemble the filter rule
+ level, err := strconv.Atoi(parts[1])
+ if err != nil {
+ return errVmoduleSyntax
+ }
+ if level <= 0 {
+ continue // Ignore. It's harmless but no point in paying the overhead.
+ }
+ // Compile the rule pattern into a regular expression
+ matcher := ".*"
+ for _, comp := range strings.Split(parts[0], "/") {
+ if comp == "*" {
+ matcher += "(/.*)?"
+ } else if comp != "" {
+ matcher += "/" + regexp.QuoteMeta(comp)
+ }
+ }
+ if !strings.HasSuffix(parts[0], ".go") {
+ matcher += "/[^/]+\\.go"
+ }
+ matcher = matcher + "$"
+
+ re, _ := regexp.Compile(matcher)
+ filter = append(filter, pattern{re, Lvl(level)})
+ }
+ // Swap out the vmodule pattern for the new filter system
+ h.lock.Lock()
+ defer h.lock.Unlock()
+
+ h.patterns = filter
+ h.siteCache = make(map[uintptr]Lvl)
+ atomic.StoreUint32(&h.override, uint32(len(filter)))
+
+ return nil
+}
+
+// BacktraceAt sets the glog backtrace location. When set to a file and line
+// number holding a logging statement, a stack trace will be written to the Info
+// log whenever execution hits that statement.
+//
+// Unlike with Vmodule, the ".go" must be present.
+func (h *GlogHandler) BacktraceAt(location string) error {
+ // Ensure the backtrace location contains two non-empty elements
+ parts := strings.Split(location, ":")
+ if len(parts) != 2 {
+ return errTraceSyntax
+ }
+ parts[0] = strings.TrimSpace(parts[0])
+ parts[1] = strings.TrimSpace(parts[1])
+ if len(parts[0]) == 0 || len(parts[1]) == 0 {
+ return errTraceSyntax
+ }
+ // Ensure the .go prefix is present and the line is valid
+ if !strings.HasSuffix(parts[0], ".go") {
+ return errTraceSyntax
+ }
+ if _, err := strconv.Atoi(parts[1]); err != nil {
+ return errTraceSyntax
+ }
+ // All seems valid
+ h.lock.Lock()
+ defer h.lock.Unlock()
+
+ h.location = location
+ atomic.StoreUint32(&h.backtrace, uint32(len(location)))
+
+ return nil
+}
+
+// Log implements Handler.Log, filtering a log record through the global, local
+// and backtrace filters, finally emitting it if either allow it through.
+func (h *GlogHandler) Log(r *Record) error {
+ // If backtracing is requested, check whether this is the callsite
+ if atomic.LoadUint32(&h.backtrace) > 0 {
+ // Everything below here is slow. Although we could cache the call sites the
+ // same way as for vmodule, backtracing is so rare it's not worth the extra
+ // complexity.
+ h.lock.RLock()
+ match := h.location == r.Call.String()
+ h.lock.RUnlock()
+
+ if match {
+ // Callsite matched, raise the log level to info and gather the stacks
+ r.Lvl = LvlInfo
+
+ buf := make([]byte, 1024*1024)
+ buf = buf[:runtime.Stack(buf, true)]
+ r.Msg += "\n\n" + string(buf)
+ }
+ }
+ // If the global log level allows, fast track logging
+ if atomic.LoadUint32(&h.level) >= uint32(r.Lvl) {
+ return h.origin.Log(r)
+ }
+ // If no local overrides are present, fast track skipping
+ if atomic.LoadUint32(&h.override) == 0 {
+ return nil
+ }
+ // Check callsite cache for previously calculated log levels
+ h.lock.RLock()
+ lvl, ok := h.siteCache[r.Call.PC()]
+ h.lock.RUnlock()
+
+ // If we didn't cache the callsite yet, calculate it
+ if !ok {
+ h.lock.Lock()
+ for _, rule := range h.patterns {
+ if rule.pattern.MatchString(fmt.Sprintf("%+s", r.Call)) {
+ h.siteCache[r.Call.PC()], lvl, ok = rule.level, rule.level, true
+ break
+ }
+ }
+ // If no rule matched, remember to drop log the next time
+ if !ok {
+ h.siteCache[r.Call.PC()] = 0
+ }
+ h.lock.Unlock()
+ }
+ if lvl >= r.Lvl {
+ return h.origin.Log(r)
+ }
+ return nil
+}