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//
// GTMSynchronizationAsserts.h
//
// Copyright 2016 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
//
#if !__has_feature(objc_arc)
#error "This file needs to be compiled with ARC enabled."
#endif
#import <Foundation/Foundation.h>
#import "GTMDefines.h" // For _GTMDevAssert.
// Macros to monitor synchronization blocks in debug builds.
//
// These report problems using _GTMDevAssert, which may be defined by the
// project or by GTMDefines.h
//
// GTMMonitorSynchronized Start monitoring a top-level-only @sync scope.
// Asserts if already inside a monitored @sync scope.
// GTMMonitorRecursiveSynchronized Start monitoring a top-level or recursive @sync
// scope.
// GTMCheckSynchronized Assert that the current execution is inside a monitored @sync
// scope.
// GTMCheckNotSynchronized Assert that the current execution is not inside a monitored
// @sync scope.
//
// Example usage:
//
// - (void)myExternalMethod {
// @synchronized(self) {
// GTMMonitorSynchronized(self)
//
// - (void)myInternalMethod {
// GTMCheckSynchronized(self);
//
// - (void)callMyCallbacks {
// GTMCheckNotSynchronized(self);
//
// GTMCheckNotSynchronized is available for verifying the code isn't
// in a deadlockable @sync state, important when posting notifications and
// invoking callbacks.
//
// Don't use GTMCheckNotSynchronized immediately before a @sync scope; the
// normal recursiveness check of GTMMonitorSynchronized can catch those.
#if DEBUG
#define __GTMMonitorSynchronizedVariableInner(varname, counter) \
varname ## counter
#define __GTMMonitorSynchronizedVariable(varname, counter) \
__GTMMonitorSynchronizedVariableInner(varname, counter)
#define GTMMonitorSynchronized(obj) \
NS_VALID_UNTIL_END_OF_SCOPE id \
__GTMMonitorSynchronizedVariable(__monitor, __COUNTER__) = \
[[GTMSyncMonitorInternal alloc] initWithSynchronizationObject:obj \
allowRecursive:NO \
functionName:__func__]
#define GTMMonitorRecursiveSynchronized(obj) \
NS_VALID_UNTIL_END_OF_SCOPE id \
__GTMMonitorSynchronizedVariable(__monitor, __COUNTER__) = \
[[GTMSyncMonitorInternal alloc] initWithSynchronizationObject:obj \
allowRecursive:YES \
functionName:__func__]
#define GTMCheckSynchronized(obj) { \
_GTMDevAssert( \
[GTMSyncMonitorInternal functionsHoldingSynchronizationOnObject:obj], \
@"GTMCheckSynchronized(" #obj ") failed: not sync'd" \
@" on " #obj " in %s. Call stack:\n%@", \
__func__, [NSThread callStackSymbols]); \
}
#define GTMCheckNotSynchronized(obj) { \
_GTMDevAssert( \
![GTMSyncMonitorInternal functionsHoldingSynchronizationOnObject:obj], \
@"GTMCheckNotSynchronized(" #obj ") failed: was sync'd" \
@" on " #obj " in %s by %@. Call stack:\n%@", __func__, \
[GTMSyncMonitorInternal functionsHoldingSynchronizationOnObject:obj], \
[NSThread callStackSymbols]); \
}
// GTMSyncMonitorInternal is a private class that keeps track of the
// beginning and end of synchronized scopes, relying on ARC to release
// it at the end of a scope.
//
// This class should not be used directly, but only via the
// GTMMonitorSynchronized macro.
@interface GTMSyncMonitorInternal : NSObject {
NSValue *_objectKey; // The synchronize target object.
const char *_functionName; // The function containing the monitored sync block.
}
- (instancetype)initWithSynchronizationObject:(id)object
allowRecursive:(BOOL)allowRecursive
functionName:(const char *)functionName;
// Return the names of the functions that hold sync on the object, or nil if none.
+ (NSArray *)functionsHoldingSynchronizationOnObject:(id)object;
@end
#else
// !DEBUG
#define GTMMonitorSynchronized(obj) do { } while (0)
#define GTMMonitorRecursiveSynchronized(obj) do { } while (0)
#define GTMCheckSynchronized(obj) do { } while (0)
#define GTMCheckNotSynchronized(obj) do { } while (0)
#endif // DEBUG
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