Bug 1380659 - Introduce code coverage component to dump/reset coverage counters. r=erahm

tools/code-coverage/CodeCoverageHandler.cpp

@@ -0,0 +1,104 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <signal.h>
+#include <stdio.h>
+#include <unistd.h>
+#include "mozilla/CodeCoverageHandler.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "nsAppRunner.h"
+
+using namespace mozilla;
+using namespace mozilla::ipc;
+
+// The __gcov_dump function writes the coverage counters to gcda files.
+// The __gcov_reset function resets the coverage counters to zero.
+// They are defined at https://github.com/gcc-mirror/gcc/blob/aad93da1a579b9ae23ede6b9cf8523360f0a08b4/libgcc/libgcov-interface.c
+// __gcov_flush is protected by a mutex, __gcov_dump and __gcov_reset aren't.
+// So we are using a CrossProcessMutex to protect them.
+
+extern "C" void __gcov_dump();
+extern "C" void __gcov_reset();
+
+StaticAutoPtr<CodeCoverageHandler> CodeCoverageHandler::instance;
+
+void CodeCoverageHandler::DumpCounters(int)
+{
+  CrossProcessMutexAutoLock lock(*CodeCoverageHandler::Get()->GetMutex());
+
+  printf_stderr("[CodeCoverage] Requested dump.\n");
+  __gcov_dump();
+  printf_stderr("[CodeCoverage] Dump completed.\n");
+}
+
+void CodeCoverageHandler::ResetCounters(int)
+{
+  CrossProcessMutexAutoLock lock(*CodeCoverageHandler::Get()->GetMutex());
+
+  printf_stderr("[CodeCoverage] Requested reset.\n");
+  __gcov_reset();
+  printf_stderr("[CodeCoverage] Reset completed.\n");
+}
+
+void CodeCoverageHandler::SetSignalHandlers()
+{
+  printf_stderr("[CodeCoverage] Setting handlers for process %d.\n", getpid());
+
+  struct sigaction dump_sa;
+  dump_sa.sa_handler = CodeCoverageHandler::DumpCounters;
+  dump_sa.sa_flags = SA_RESTART;
+  sigemptyset(&dump_sa.sa_mask);
+  MOZ_ASSERT(sigaction(SIGUSR1, &dump_sa, nullptr) == 0);
+
+  struct sigaction reset_sa;
+  reset_sa.sa_handler = CodeCoverageHandler::ResetCounters;
+  reset_sa.sa_flags = SA_RESTART;
+  sigemptyset(&reset_sa.sa_mask);
+  MOZ_ASSERT(sigaction(SIGUSR2, &reset_sa, nullptr) == 0);
+}
+
+CodeCoverageHandler::CodeCoverageHandler()
+  : mGcovLock("GcovLock")
+{
+  SetSignalHandlers();
+}
+
+CodeCoverageHandler::CodeCoverageHandler(const CrossProcessMutexHandle& aHandle)
+  : mGcovLock(aHandle)
+{
+  SetSignalHandlers();
+}
+
+void CodeCoverageHandler::Init()
+{
+  MOZ_ASSERT(!instance);
+  MOZ_ASSERT(XRE_IsParentProcess());
+  instance = new CodeCoverageHandler();
+  ClearOnShutdown(&instance);
+}
+
+void CodeCoverageHandler::Init(const CrossProcessMutexHandle& aHandle)
+{
+  MOZ_ASSERT(!instance);
+  MOZ_ASSERT(!XRE_IsParentProcess());
+  instance = new CodeCoverageHandler(aHandle);
+  ClearOnShutdown(&instance);
+}
+
+CodeCoverageHandler* CodeCoverageHandler::Get()
+{
+  MOZ_ASSERT(instance);
+  return instance;
+}
+
+CrossProcessMutex* CodeCoverageHandler::GetMutex()
+{
+  return &mGcovLock;
+}
+
+CrossProcessMutexHandle CodeCoverageHandler::GetMutexHandle(int aProcId)
+{
+  return mGcovLock.ShareToProcess(aProcId);
+}