Add a log_allocator_stats_on_exit option.

Running some types of executables, you want to get the stats at
the end of the run. Therefore, add an option to dump the allocator
stats when the program finishes.

Add new unit tests to cover this new option.

Test: All unit tests pass.
Test: Enabled the option, ran getprop and verified that the
Test: log contains the allocator stats.
Change-Id: I1c9f7d5a1fe374e8cfb6ffc8d1caa59064c5d55e

Author: cferris1000

libc/malloc_debug/Config.cpp

@@ -212,6 +212,10 @@ const std::unordered_map<std::string, Config::OptionInfo> Config::kOptions = {
         "log_allocator_stats_on_signal",
         {LOG_ALLOCATOR_STATS_ON_SIGNAL, &Config::VerifyValueEmpty},
     },
+    {
+        "log_allocator_stats_on_exit",
+        {LOG_ALLOCATOR_STATS_ON_EXIT, &Config::VerifyValueEmpty},
+    },
 };
 
 bool Config::ParseValue(const std::string& option, const std::string& value, size_t min_value,

libc/malloc_debug/Config.h

@@ -49,6 +49,7 @@ constexpr uint64_t VERBOSE = 0x1000;
 constexpr uint64_t CHECK_UNREACHABLE_ON_SIGNAL = 0x2000;
 constexpr uint64_t BACKTRACE_SPECIFIC_SIZES = 0x4000;
 constexpr uint64_t LOG_ALLOCATOR_STATS_ON_SIGNAL = 0x8000;
+constexpr uint64_t LOG_ALLOCATOR_STATS_ON_EXIT = 0x10000;
 
 // In order to guarantee posix compliance, set the minimum alignment
 // to 8 bytes for 32 bit systems and 16 bytes for 64 bit systems.

libc/malloc_debug/LogAllocatorStats.cpp

@@ -43,13 +43,17 @@ static void CallMalloptLogStats(int, struct siginfo*, void*) {
   g_call_mallopt = true;
 }
 
+void Log() {
+  info_log("Logging allocator stats...");
+  if (mallopt(M_LOG_STATS, 0) == 0) {
+    error_log("mallopt(M_LOG_STATS, 0) call failed.");
+  }
+}
+
 void CheckIfShouldLog() {
   bool expected = true;
   if (g_call_mallopt.compare_exchange_strong(expected, false)) {
-    info_log("Logging allocator stats...");
-    if (mallopt(M_LOG_STATS, 0) == 0) {
-      error_log("mallopt(M_LOG_STATS, 0) call failed.");
-    }
+    Log();
   }
 }
 

libc/malloc_debug/LogAllocatorStats.h

@@ -35,6 +35,8 @@ namespace LogAllocatorStats {
 
 bool Initialize(const Config& config);
 
+void Log();
+
 void CheckIfShouldLog();
 
 }  // namespace LogAllocatorStats

libc/malloc_debug/malloc_debug.cpp

@@ -461,6 +461,10 @@ void debug_finalize() {
                                                 getpid()).c_str());
   }
 
+  if (g_debug->config().options() & LOG_ALLOCATOR_STATS_ON_EXIT) {
+    LogAllocatorStats::Log();
+  }
+
   backtrace_shutdown();
 
   // In order to prevent any issues of threads freeing previous pointers

libc/malloc_debug/tests/malloc_debug_config_tests.cpp

@@ -861,6 +861,24 @@ TEST_F(MallocDebugConfigTest, trigger_log_allocator_stats_on_signal_fail) {
   ASSERT_STREQ((log_msg + usage_string).c_str(), getFakeLogPrint().c_str());
 }
 
+TEST_F(MallocDebugConfigTest, log_allocator_stats_on_exit) {
+  ASSERT_TRUE(InitConfig("log_allocator_stats_on_exit")) << getFakeLogPrint();
+  ASSERT_EQ(LOG_ALLOCATOR_STATS_ON_EXIT, config->options());
+
+  ASSERT_STREQ("", getFakeLogBuf().c_str());
+  ASSERT_STREQ("", getFakeLogPrint().c_str());
+}
+
+TEST_F(MallocDebugConfigTest, trigger_log_allocator_stats_on_exit_fail) {
+  ASSERT_FALSE(InitConfig("log_allocator_stats_on_exit=200")) << getFakeLogPrint();
+
+  ASSERT_STREQ("", getFakeLogBuf().c_str());
+  std::string log_msg(
+      "6 malloc_debug malloc_testing: value set for option 'log_allocator_stats_on_exit' "
+      "which does not take a value\n");
+  ASSERT_STREQ((log_msg + usage_string).c_str(), getFakeLogPrint().c_str());
+}
+
 TEST_F(MallocDebugConfigTest, size) {
   ASSERT_TRUE(InitConfig("backtrace_size=37")) << getFakeLogPrint();
   ASSERT_EQ(BACKTRACE_SPECIFIC_SIZES, config->options());

libc/malloc_debug/tests/malloc_debug_unit_tests.cpp

@@ -426,7 +426,7 @@ TEST_F(MallocDebugTest, all_options) {
   Init(
       "guard backtrace backtrace_enable_on_signal fill expand_alloc free_track leak_track "
       "record_allocs verify_pointers abort_on_error verbose check_unreachable_on_signal "
-      "log_allocator_stats_on_signal");
+      "log_allocator_stats_on_signal log_allocator_stats_on_exit");
   VerifyAllocCalls(true);
 }
 
@@ -2844,6 +2844,25 @@ TEST_F(MallocDebugTest, log_allocator_stats_on_signal) {
   }
 }
 
+TEST_F(MallocDebugTest, log_allocator_stats_on_exit) {
+  Init("log_allocator_stats_on_exit");
+
+  void* pointer = debug_malloc(110);
+  ASSERT_TRUE(pointer != nullptr);
+  debug_free(pointer);
+
+  debug_finalize();
+
+  ASSERT_STREQ("", getFakeLogBuf().c_str());
+  if (!running_with_hwasan()) {
+    // Do an exact match because the mallopt should not fail in normal operation.
+    ASSERT_STREQ("4 malloc_debug Logging allocator stats...\n", getFakeLogPrint().c_str());
+  } else {
+    // mallopt fails with hwasan, so just verify that the message is present.
+    ASSERT_MATCH(getFakeLogPrint(), "4 malloc_debug Logging allocator stats...\\n");
+  }
+}
+
 TEST_F(MallocDebugTest, backtrace_only_some_sizes_with_backtrace_size) {
   Init("leak_track backtrace backtrace_size=120");