libs-base/Tests/base/NSObject/initialize.m

#import <Foundation/NSThread.h>
#import <Foundation/NSLock.h>
#include <unistd.h>
#import "Testing.h"

@interface SlowInit0
@end

@interface SlowInit1 : SlowInit0 
+ (void) doNothing;
@end

@interface SlowInit2
+ (void) doNothing;
@end

static NSCondition *l;
static volatile int init0, init1, init2, init3;

@implementation SlowInit0
+ (void) initialize
{
  init0 = 1;
}
@end

@implementation SlowInit1
/**
 * Called from main thread.
 */
+ (void) initialize
{
  PASS(init0 == 1, "Superclass +initialize called before subclass");
  // Spin until we've entered the second +initialize method
  while (init2 == 0) {}
  // Wake up the other thread
  [l signal];
  [l unlock];
  // Trigger the 
  [SlowInit2 doNothing];
  init1 = 1;
}
+ (void) doNothing {}
@end

@implementation SlowInit2
/**
 * Called from the second thread. 
 */
+ (void) initialize
{
  init2++;
  // Sleep until the main thread is ready for us
  [l lock];
  /* If the runtime is doing the wrong thing and this is called twice, then
   * there will be no signal.  We don't want to deadlock, so make sure that
   * this times out after a short while.
   */
  [l waitUntilDate: [NSDate dateWithTimeIntervalSinceNow: 1.5]];
  [l unlock];
  [NSThread sleepForTimeInterval: 1];
  PASS(init1 == 0, "First initialize method did not finish too early");
  init3++;
}
static volatile int finished = 2;
+ (void) doNothing
{
  PASS(init2 == 1, "+initialize called exactly once");
  PASS(init3 == 1, "+initialize completed before another method started");
  finished--;
}
@end

@interface Trampoline : NSObject
+ (void) launch: (id)ignored;
@end

@implementation Trampoline
/**
 * Launch the second thread.  NSThread retains its arguments in the main
 * thread, we need to ensure that nothing triggers the second +initialize
 * method until we're in the second thread.
 */
+ (void) launch: (id)ignored
{
  [NSAutoreleasePool new];
  [SlowInit2 doNothing];
}
@end

static void
alarmed(int sig)
{
  /* Generate a dashed hope for concurrency testing.
   */
  testHopeful = YES;
  PASS(0, "+initialize runs concurrently");
  exit(0);
}

/**
 * Test the behaviour of +initialize.
 * It's an undocumented (but nivce) feature that the Apple runtime lets
 * both of the +initialize methods run concurrently, however the first
 * one will block implicitly until the second one has completed.
 */
int main(void)
{
  [NSAutoreleasePool new];

  /* Make sure we have initalised all the classes necessary for the test
   * framework to record a test ... by passing one.
   */
  PASS(1, "initialize test starts");

#if defined(SIGALRM)
  /* End in a signal if the concurrency test deadlocks.
   */
  signal(SIGALRM, alarmed);
  alarm(5);
#else
  SKIP("+initialize runs concurrently");
#endif

  l = [NSCondition new];
  [l lock];
  [NSThread detachNewThreadSelector: @selector(launch:)
			   toTarget: [Trampoline class]
			 withObject: nil];
  [NSThread sleepForTimeInterval: 0.5];
  [SlowInit1 doNothing];
  [l lock];
  [l unlock];
  while (finished)
    {
      [NSThread sleepForTimeInterval: 0.01];
    }
  return 0;
}