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Clean mutexes as part of garbage collection cycle instead of uv_async #880

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Merged
johnhaley81 merged 1 commit into from
Jan 28, 2016
Merged

Clean mutexes as part of garbage collection cycle instead of uv_async #880

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27 changes: 12 additions & 15 deletions generate/templates/manual/src/lock_master.cc
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
#include <nan.h>
#include <git2.h>
#include <uv.h>
#include <set>
Expand Down Expand Up @@ -31,10 +32,8 @@ class LockMasterImpl {
// A libuv key used to store the current thread-specific LockMasterImpl instance
static uv_key_t currentLockMasterKey;

// A libuv async handle used to trigger / debounce mutex cleanup
static uv_async_t cleanupMutexesHandle;
// Cleans up any mutexes that are not currently used
static void CleanupMutexes(uv_async_t *async);
static NAN_GC_CALLBACK(CleanupMutexes);

public:
static void Initialize();
Expand All @@ -49,7 +48,6 @@ class LockMasterImpl {
std::vector<uv_mutex_t *> GetMutexes(int useCountDelta);
void Register();
void Unregister();
void CleanupMutexes();

public:
static LockMasterImpl *CurrentLockMasterImpl() {
Expand All @@ -64,7 +62,6 @@ class LockMasterImpl {
~LockMasterImpl() {
Unregister();
Unlock(true);
CleanupMutexes();
}

void ObjectToLock(const void *objectToLock) {
Expand All @@ -78,16 +75,22 @@ class LockMasterImpl {
std::map<const void *, ObjectInfo> LockMasterImpl::mutexes;
uv_mutex_t LockMasterImpl::mapMutex;
uv_key_t LockMasterImpl::currentLockMasterKey;
uv_async_t LockMasterImpl::cleanupMutexesHandle;


void LockMasterImpl::Initialize() {
uv_mutex_init(&mapMutex);
uv_key_create(&currentLockMasterKey);
uv_async_init(uv_default_loop(), &cleanupMutexesHandle, CleanupMutexes);
Nan::AddGCEpilogueCallback(CleanupMutexes);
}

void LockMasterImpl::CleanupMutexes(uv_async_t *async) {
NAN_GC_CALLBACK(LockMasterImpl::CleanupMutexes) {
// skip cleanup if thread safety is disabled
// this means that turning thread safety on and then off
// could result in remaining mutexes - but they would get cleaned up
// if thread safety is turned on again
if (!LockMaster::IsEnabled()) {
return;
}

uv_mutex_lock(&mapMutex);

for (auto it = mutexes.begin(); it != mutexes.end(); )
Expand Down Expand Up @@ -197,12 +200,6 @@ void LockMasterImpl::Unlock(bool releaseMutexes) {
GetMutexes(releaseMutexes * -1);
}

void LockMasterImpl::CleanupMutexes() {
// schedule mutex cleanup on the main event loop
// this somewhat delays and debounces cleanup (uv_async_send coalesces calls)
uv_async_send(&cleanupMutexesHandle);
}

LockMaster::Diagnostics LockMasterImpl::GetDiagnostics() {
LockMaster::Diagnostics diagnostics;
uv_mutex_lock(&LockMasterImpl::mapMutex);
Expand Down
11 changes: 7 additions & 4 deletions test/tests/thread_safety.js
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Original file line number Diff line number Diff line change
Expand Up @@ -42,18 +42,21 @@ describe("ThreadSafety", function() {
}
});

it("can lock something", function() {
it("can lock something and cleanup mutex", function() {
// call a sync method to guarantee that it stores a mutex,
// and that it will not clean up the mutex (since the cleanup is
// scheduled on the main node thread)
// and that it will clean up the mutex in a garbage collection cycle
this.repository.headDetached();

var diagnostics = NodeGit.getThreadSafetyDiagnostics();
if (diagnostics.isEnabled) {
if (NodeGit.isThreadSafetyEnabled()) {
// this is a fairly vague test - it just tests that something
// had a mutex created for it at some point (i.e., the thread safety
// code is not completely dead)
assert.ok(diagnostics.storedMutexesCount > 0);
// now test that GC cleans up mutexes
global.gc();
diagnostics = NodeGit.getThreadSafetyDiagnostics();
assert.equal(0, diagnostics.storedMutexesCount);
} else {
assert.equal(0, diagnostics.storedMutexesCount);
}
Expand Down