semaphore.cpp

Engine/source/platformX86UNIX/threads/semaphore.cpp
Classes:

class
Detailed Description

 1
 2//-----------------------------------------------------------------------------
 3// Copyright (c) 2012 GarageGames, LLC
 4//
 5// Permission is hereby granted, free of charge, to any person obtaining a copy
 6// of this software and associated documentation files (the "Software"), to
 7// deal in the Software without restriction, including without limitation the
 8// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 9// sell copies of the Software, and to permit persons to whom the Software is
10// furnished to do so, subject to the following conditions:
11//
12// The above copyright notice and this permission notice shall be included in
13// all copies or substantial portions of the Software.
14//
15// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21// IN THE SOFTWARE.
22//-----------------------------------------------------------------------------
23
24#include "platformX86UNIX/platformX86UNIX.h"
25#include "platform/threads/semaphore.h"
26// Instead of that mess that was here before, lets use the SDL lib to deal
27// with the semaphores.
28
29#include <SDL.h>
30#include <SDL_thread.h>
31
32struct PlatformSemaphore
33{
34   SDL_sem *semaphore;
35
36   PlatformSemaphore(S32 initialCount)
37   {
38       semaphore = SDL_CreateSemaphore(initialCount);
39       AssertFatal(semaphore, "PlatformSemaphore constructor - Failed to create SDL Semaphore.");
40   }
41
42   ~PlatformSemaphore()
43   {
44       SDL_DestroySemaphore(semaphore);
45   }
46};
47
48Semaphore::Semaphore(S32 initialCount)
49{
50  mData = new PlatformSemaphore(initialCount);
51}
52
53Semaphore::~Semaphore()
54{
55  AssertFatal(mData, "Semaphore destructor - Invalid semaphore.");
56  delete mData;
57}
58
59bool Semaphore::acquire(bool block, S32 timeoutMS)
60{
61   AssertFatal(mData && mData->semaphore, "Semaphore::acquire - Invalid semaphore.");
62   if (block)
63   {
64      // Semaphore acquiring is different from the MacOS/Win realization because SDL_SemWaitTimeout() with "infinite" timeout can be too heavy on some platforms.
65      // (see "man SDL_SemWaitTimeout(3)" for more info)
66      // "man" states to avoid the use of SDL_SemWaitTimeout at all, but at current stage this looks like a valid and working solution, so keeping it this way.
67      // [bank / Feb-2010]
68      if (timeoutMS == -1)
69      {
70         if (SDL_SemWait(mData->semaphore) < 0)
71            AssertFatal(false, "Semaphore::acquie - Wait failed.");
72      }
73      else
74      {
75         if (SDL_SemWaitTimeout(mData->semaphore, timeoutMS) < 0)
76            AssertFatal(false, "Semaphore::acquie - Wait with timeout failed.");
77      }
78      return (true);
79   }
80   else
81   {
82      int res = SDL_SemTryWait(mData->semaphore);
83      return (res == 0);
84   }
85}
86
87void Semaphore::release()
88{
89   AssertFatal(mData, "Semaphore::releaseSemaphore - Invalid semaphore.");
90   SDL_SemPost(mData->semaphore);
91}
92