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author | Thomas Van Lenten <thomasvl@google.com> | 2016-03-21 11:11:14 -0400 |
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committer | Thomas Van Lenten <thomasvl@google.com> | 2016-03-21 11:11:14 -0400 |
commit | bd41a39f693d8307d407e42b634b315e075b6c8f (patch) | |
tree | 018b7755a546f18ee54e3fc48d6f8c69fdbcc67d | |
parent | 5e933847cc9e7826f1a9ee8b3dc1df4960b1ea5d (diff) | |
download | protobuf-bd41a39f693d8307d407e42b634b315e075b6c8f.tar.gz protobuf-bd41a39f693d8307d407e42b634b315e075b6c8f.tar.bz2 protobuf-bd41a39f693d8307d407e42b634b315e075b6c8f.zip |
Only create the readonlySemaphore on demand.
This will lower the amount of dispatch_semaphores created per Message when the
full object tree isn't walked in a way that would require them to be created.
Uses a dispatch_once_t for one time init of the dispatch_semaphore.
-rw-r--r-- | objectivec/GPBMessage.m | 9 | ||||
-rw-r--r-- | objectivec/GPBMessage_PackagePrivate.h | 12 | ||||
-rw-r--r-- | objectivec/GPBUtilities.m | 1 |
3 files changed, 19 insertions, 3 deletions
diff --git a/objectivec/GPBMessage.m b/objectivec/GPBMessage.m index 94d179be..3da85b5b 100644 --- a/objectivec/GPBMessage.m +++ b/objectivec/GPBMessage.m @@ -556,6 +556,7 @@ static id GetArrayIvarWithField(GPBMessage *self, GPBFieldDescriptor *field) { id array = GPBGetObjectIvarWithFieldNoAutocreate(self, field); if (!array) { // Check again after getting the lock. + GPBPrepareReadOnlySemaphore(self); dispatch_semaphore_wait(self->readOnlySemaphore_, DISPATCH_TIME_FOREVER); array = GPBGetObjectIvarWithFieldNoAutocreate(self, field); if (!array) { @@ -586,6 +587,7 @@ static id GetMapIvarWithField(GPBMessage *self, GPBFieldDescriptor *field) { id dict = GPBGetObjectIvarWithFieldNoAutocreate(self, field); if (!dict) { // Check again after getting the lock. + GPBPrepareReadOnlySemaphore(self); dispatch_semaphore_wait(self->readOnlySemaphore_, DISPATCH_TIME_FOREVER); dict = GPBGetObjectIvarWithFieldNoAutocreate(self, field); if (!dict) { @@ -791,8 +793,6 @@ static GPBUnknownFieldSet *GetOrMakeUnknownFields(GPBMessage *self) { if ((self = [super init])) { messageStorage_ = (GPBMessage_StoragePtr)( ((uint8_t *)self) + class_getInstanceSize([self class])); - - readOnlySemaphore_ = dispatch_semaphore_create(1); } return self; @@ -868,7 +868,9 @@ static GPBUnknownFieldSet *GetOrMakeUnknownFields(GPBMessage *self) { - (void)dealloc { [self internalClear:NO]; NSCAssert(!autocreator_, @"Autocreator was not cleared before dealloc."); - dispatch_release(readOnlySemaphore_); + if (readOnlySemaphore_) { + dispatch_release(readOnlySemaphore_); + } [super dealloc]; } @@ -1706,6 +1708,7 @@ static GPBUnknownFieldSet *GetOrMakeUnknownFields(GPBMessage *self) { } // Check for an autocreated value. + GPBPrepareReadOnlySemaphore(self); dispatch_semaphore_wait(readOnlySemaphore_, DISPATCH_TIME_FOREVER); value = [autocreatedExtensionMap_ objectForKey:extension]; if (!value) { diff --git a/objectivec/GPBMessage_PackagePrivate.h b/objectivec/GPBMessage_PackagePrivate.h index b7e24fc9..478db2cf 100644 --- a/objectivec/GPBMessage_PackagePrivate.h +++ b/objectivec/GPBMessage_PackagePrivate.h @@ -67,6 +67,10 @@ typedef struct GPBMessage_Storage *GPBMessage_StoragePtr; // priority inversion: // http://mjtsai.com/blog/2015/12/16/osspinlock-is-unsafe/ // https://lists.swift.org/pipermail/swift-dev/Week-of-Mon-20151214/000372.html + // Use of readOnlySemaphore_ must be prefaced by a call to + // GPBPrepareReadOnlySemaphore to ensure it has been created. This allows + // readOnlySemaphore_ to be only created when actually needed. + dispatch_once_t readOnlySemaphoreCreationOnce_; dispatch_semaphore_t readOnlySemaphore_; } @@ -103,6 +107,14 @@ typedef struct GPBMessage_Storage *GPBMessage_StoragePtr; CF_EXTERN_C_BEGIN + +// Call this before using the readOnlySemaphore_. This ensures it is created only once. +NS_INLINE void GPBPrepareReadOnlySemaphore(GPBMessage *self) { + dispatch_once(&self->readOnlySemaphoreCreationOnce_, ^{ + self->readOnlySemaphore_ = dispatch_semaphore_create(1); + }); +} + // Returns a new instance that was automatically created by |autocreator| for // its field |field|. GPBMessage *GPBCreateMessageWithAutocreator(Class msgClass, diff --git a/objectivec/GPBUtilities.m b/objectivec/GPBUtilities.m index 3e9d11c0..447c749a 100644 --- a/objectivec/GPBUtilities.m +++ b/objectivec/GPBUtilities.m @@ -412,6 +412,7 @@ id GPBGetObjectIvarWithField(GPBMessage *self, GPBFieldDescriptor *field) { return field.defaultValue.valueMessage; } + GPBPrepareReadOnlySemaphore(self); dispatch_semaphore_wait(self->readOnlySemaphore_, DISPATCH_TIME_FOREVER); GPBMessage *result = GPBGetObjectIvarWithFieldNoAutocreate(self, field); if (!result) { |