NSOperationQueue: Proper names for worker threads (#437)

* NSOperationQueue: Give Worker Threads a name

* Update Changelog

* Remove empty string test

ChangeLog

@@ -1,3 +1,10 @@
+2024-13-08: Hugo Melder <[email protected]>
+
+ * Source/NSOperation.m:
+ * Headers/Foundation/NSOperation.h:
+ Give NSOperationQueue worker threads a proper thread
+ name for easy identification.
+
 2024-12-08 Hugo Melder <[email protected]>
  * Source/NSThread.m:
  Fix threadPriority and setThreadPriority: on Android.

Headers/Foundation/NSOperation.h

@@ -224,6 +224,17 @@ enum {
  NSOperationQueueDefaultMaxConcurrentOperationCount = -1
 };
 
+/**
+ * An NSOperationQueue manages a number of NSOperation objects, scheduling
+ * them for execution and managing their dependencies.
+ *
+ * Depending on the configuration of the queue, operations may be executed
+ * concurrently or serially.
+ *
+ * Worker threads are named "NSOperationQ_<number>" by default, but
+ * you can set a name for the queue using the -setName: method.
+ * The suffix "_<number>"" is automatically added to the thread name.
+ */
 GS_EXPORT_CLASS
 @interface NSOperationQueue : NSObject
 {

Source/NSOperation.m

@@ -50,6 +50,7 @@
  NSMutableArray *waiting; \
  NSMutableArray *starting; \
  NSString *name; \
+ NSString *threadName; \
  BOOL suspended; \
  NSInteger executing; \
  NSInteger threadCount; \
@@ -63,6 +64,7 @@
 #import "Foundation/NSException.h"
 #import "Foundation/NSKeyValueObserving.h"
 #import "Foundation/NSThread.h"
+#import "Foundation/NSValue.h"
 #import "GNUstepBase/NSArray+GNUstepBase.h"
 #import "GSPrivate.h"
 
@@ -614,7 +616,7 @@ - (void) main
 
 @interface NSOperationQueue (Private)
 - (void) _execute;
-- (void) _thread;
+- (void) _thread: (NSNumber *) threadNumber;
 - (void) observeValueForKeyPath: (NSString *)keyPath
  ofObject: (id)object
  change: (NSDictionary *)change
@@ -831,6 +833,15 @@ - (id) init
  internal->cond = [[NSConditionLock alloc] initWithCondition: 0];
  [internal->cond setName:
  [NSString stringWithFormat: @"cond-for-op-%p", self]];
+ internal->name = [[NSString alloc] initWithFormat: @"NSOperationQueue %p", self];
+
+ /* Ensure that default thread name can be displayed on systems with a
+ * limited thread name length.
+ *
+ * This value is set to internal->name, when altered with -setName:
+ * Worker threads are not renamed during their lifetime.
+ */
+ internal->threadName = @"NSOperationQ";
  }
  return self;
 }
@@ -850,13 +861,9 @@ - (NSString*) name
  NSString *s;
 
  [internal->lock lock];
- if (internal->name == nil)
- {
- internal->name
- = [[NSString alloc] initWithFormat: @"NSOperation %p", self];
- }
- s = RETAIN(internal->name);
+ s = [internal->name copy];
  [internal->lock unlock];
+
  return AUTORELEASE(s);
 }
 
@@ -902,13 +909,16 @@ - (void) setMaxConcurrentOperationCount: (NSInteger)cnt
 
 - (void) setName: (NSString*)s
 {
- if (s == nil) s = @"";
+ if (s == nil) return;
+
  [internal->lock lock];
  if (NO == [internal->name isEqual: s])
  {
  [self willChangeValueForKey: @"name"];
  RELEASE(internal->name);
  internal->name = [s copy];
+ // internal->threadName is unretained
+ internal->threadName = internal->name;
  [self didChangeValueForKey: @"name"];
  }
  [internal->lock unlock];
@@ -1000,12 +1010,22 @@ - (void) observeValueForKeyPath: (NSString *)keyPath
  [self _execute];
 }
 
-- (void) _thread
+- (void) _thread: (NSNumber *) threadNumber
 {
+ NSString *tName;
+ NSThread *current;
+
  CREATE_AUTORELEASE_POOL(arp);
 
- [[[NSThread currentThread] threadDictionary] setObject: self
- forKey: threadKey];
+ current = [NSThread currentThread];
+
+ [internal->lock lock];
+ tName = [internal->threadName stringByAppendingFormat: @"_%@", threadNumber];
+ [internal->lock unlock];
+
+ [[current threadDictionary] setObject: self forKey: threadKey];
+ [current setName: tName];
+
  for (;;)
  {
  NSOperation *op;
@@ -1125,9 +1145,10 @@ - (void) _execute
  internal->threadCount++;
  NS_DURING
  {
- [NSThread detachNewThreadSelector: @selector(_thread)
+ NSNumber *threadNumber = [NSNumber numberWithInteger: internal->threadCount - 1];
+ [NSThread detachNewThreadSelector: @selector(_thread:)
  toTarget: self
- withObject: nil];
+ withObject: threadNumber];
  }
  NS_HANDLER
  {

Tests/base/NSOperation/basic.m

@@ -107,8 +107,6 @@ int main()
  PASS(([[obj1 name] length] > 0), "name has a default");
  [obj1 setName: @"mine"];
  PASS(([[obj1 name] isEqual: @"mine"] == YES), "set name OK");
- [obj1 setName: nil];
- PASS(([[obj1 name] isEqual: @""]), "setting null name gives empty string");
 
  PASS(([obj1 maxConcurrentOperationCount] == NSOperationQueueDefaultMaxConcurrentOperationCount), "max concurrent set by default");
  [obj1 setMaxConcurrentOperationCount: 1];