support multiple log message handlers in base/logging.h

base/logging.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/logging.h"
 
 #include <limits.h>
 #include <stdint.h>
 
 #include "base/macros.h"
@@ skipping 34 matching lines @@
 typedef FILE* FileHandle;
 typedef pthread_mutex_t* MutexHandle;
 #endif
 
 #include <algorithm>
 #include <cstring>
 #include <ctime>
 #include <iomanip>
 #include <ostream>
 #include <string>
+#include <vector>
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/debug/alias.h"
 #include "base/debug/debugger.h"
 #include "base/debug/stack_trace.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
@@ skipping 51 matching lines @@
 bool g_log_thread_id = false;
 bool g_log_timestamp = true;
 bool g_log_tickcount = false;
 
 // Should we pop up fatal debug messages in a dialog?
 bool show_error_dialogs = false;
 
 // An assert handler override specified by the client to be called instead of
 // the debug message dialog and process termination.
 LogAssertHandlerFunction log_assert_handler = nullptr;
-// A log message handler that gets notified of every log message we process.
-LogMessageHandlerFunction log_message_handler = nullptr;
+// Log message handlers that get notified of every log message we process.
+std::vector<LogMessageHandlerFunction>* log_message_handlers = nullptr;
 
 // Helper functions to wrap platform differences.
 
 int32_t CurrentProcessId() {
 #if defined(OS_WIN)
   return GetCurrentProcessId();
 #elif defined(OS_POSIX)
   return getpid();
 #endif
 }
@@ skipping 264 matching lines @@
   return g_min_log_level;
 }
 
 bool ShouldCreateLogMessage(int severity) {
   if (severity < g_min_log_level)
     return false;
 
   // Return true here unless we know ~LogMessage won't do anything. Note that
   // ~LogMessage writes to stderr if severity_ >= kAlwaysPrintErrorLevel, even
   // when g_logging_destination is LOG_NONE.
-  return g_logging_destination != LOG_NONE || log_message_handler ||
+  return g_logging_destination != LOG_NONE ||
+         (log_message_handlers && log_message_handlers->size() > 0) ||
          severity >= kAlwaysPrintErrorLevel;
 }
 
 int GetVlogVerbosity() {
   return std::max(-1, LOG_INFO - GetMinLogLevel());
 }
 
 int GetVlogLevelHelper(const char* file, size_t N) {
   DCHECK_GT(N, 0U);
   // Note: |g_vlog_info| may change on a different thread during startup
@@ skipping 13 matching lines @@
 }
 
 void SetShowErrorDialogs(bool enable_dialogs) {
   show_error_dialogs = enable_dialogs;
 }
 
 void SetLogAssertHandler(LogAssertHandlerFunction handler) {
   log_assert_handler = handler;
 }
 
-void SetLogMessageHandler(LogMessageHandlerFunction handler) {
-  log_message_handler = handler;
+void AddLogMessageHandler(LogMessageHandlerFunction handler) {
+  if (!log_message_handlers)
+    log_message_handlers = new std::vector<LogMessageHandlerFunction>;
+  DCHECK_EQ(0, std::count(log_message_handlers->begin(),
+                          log_message_handlers->end(), handler));
+  log_message_handlers->push_back(handler);
 }
 
-LogMessageHandlerFunction GetLogMessageHandler() {
-  return log_message_handler;
+void RemoveLogMessageHandler(LogMessageHandlerFunction handler) {
+  if (log_message_handlers) {
+    auto it = std::find(log_message_handlers->begin(),
+                        log_message_handlers->end(), handler);
+    if (it != log_message_handlers->end()) {
+      log_message_handlers->erase(it);
+      return;
+    }
+  }
+  NOTREACHED();
 }
 
 // Explicit instantiations for commonly used comparisons.
 template std::string* MakeCheckOpString<int, int>(
     const int&, const int&, const char* names);
 template std::string* MakeCheckOpString<unsigned long, unsigned long>(
     const unsigned long&, const unsigned long&, const char* names);
 template std::string* MakeCheckOpString<unsigned long, unsigned int>(
     const unsigned long&, const unsigned int&, const char* names);
 template std::string* MakeCheckOpString<unsigned int, unsigned long>(
@@ skipping 69 matching lines @@
     // Include a stack trace on a fatal, unless a debugger is attached.
     base::debug::StackTrace trace;
     stream_ << std::endl;  // Newline to separate from log message.
     trace.OutputToStream(&stream_);
   }
 #endif
   stream_ << std::endl;
   std::string str_newline(stream_.str());
 
   // Give any log message handler first dibs on the message.
-  if (log_message_handler &&
-      log_message_handler(severity_, file_, line_,
-                          message_start_, str_newline)) {
-    // The handler took care of it, no further processing.
-    return;
+  if (log_message_handlers) {
+    const std::string message = str_newline.substr(message_start_);
+    if (std::count_if(log_message_handlers->begin(),
+                      log_message_handlers->end(),
+                      [this, &message](auto handler) {
+                        return handler(severity_, file_, line_, message);
+                      }) > 0) {
+      // At least one of the handlers took care of it, no further processing.
+      return;
+    }
   }
 
   if ((g_logging_destination & LOG_TO_SYSTEM_DEBUG_LOG) != 0) {
 #if defined(OS_WIN)
     OutputDebugStringA(str_newline.c_str());
 #elif defined(OS_MACOSX)
     // In LOG_TO_SYSTEM_DEBUG_LOG mode, log messages are always written to
     // stderr. If stderr is /dev/null, also log via ASL (Apple System Log). If
     // there's something weird about stderr, assume that log messages are going
     // nowhere and log via ASL too. Messages logged via ASL show up in
@@ skipping 365 matching lines @@
 BASE_EXPORT void LogErrorNotReached(const char* file, int line) {
   LogMessage(file, line, LOG_ERROR).stream()
       << "NOTREACHED() hit.";
 }
 
 }  // namespace logging
 
 std::ostream& std::operator<<(std::ostream& out, const wchar_t* wstr) {
   return out << (wstr ? base::WideToUTF8(wstr) : std::string());
 }