sync__unix_8h-source.html

FastDb是高效的内存数据库系统

00541     <span class="keywordtype">void</span> erase();
00542 };
00543 
00544 <span class="keyword">class </span>dbEvent { 
00545     <span class="keywordtype">int</span> e;
00546   <span class="keyword">public</span>:
00547     <span class="keywordtype">bool</span> wait(<span class="keywordtype">unsigned</span> msec = INFINITE);
00548     <span class="keywordtype">void</span> signal();
00549     <span class="keywordtype">void</span> reset();
00550     <span class="keywordtype">bool</span> open(<span class="keywordtype">char</span> <span class="keyword">const</span>* name, <span class="keywordtype">bool</span> signaled = <span class="keyword">false</span>);
00551     <span class="keywordtype">void</span> close();
00552     <span class="keywordtype">void</span> erase();
00553 };
00554 <span class="preprocessor">#endif // USE_POSIX_SEMAPHORES</span>
00555 <span class="preprocessor"></span>
00556 
00557 <span class="comment">// Define dbSharedObject and dbSharedMemory</span>
00558 <span class="preprocessor">#if defined(USE_POSIX_MMAP) &amp;&amp; USE_POSIX_MMAP</span>
00559 <span class="preprocessor"></span>
00560 <span class="comment">// For POSIX dbSharedObject, we use mmap()</span>
00561 <span class="keyword">template</span>&lt;<span class="keyword">class</span> T&gt;
00562 <span class="keyword">class </span>dbSharedObject { 
00563     <span class="keywordtype">char</span>* name;
00564     T*  ptr;
00565     <span class="keywordtype">int</span> fd;
00566   <span class="keyword">public</span>:
00567 
00568     dbSharedObject() { 
00569         name = NULL;
00570         ptr = NULL;
00571         fd = -1;
00572     }
00573 
00574     <span class="keywordtype">bool</span> open(<span class="keywordtype">char</span>* fileName) { 
00575         <span class="keyword">delete</span>[] name;
00576         name = <span class="keyword">new</span> <span class="keywordtype">char</span>[strlen(fileName) + 1];
00577         strcpy(name, fileName);
00578         fd = ::open(fileName, O_RDWR|O_CREAT, 0777);
00579         <span class="keywordflow">if</span> (fd &lt; 0) { 
00580             <span class="keywordflow">return</span> <span class="keyword">false</span>;
00581         }
00582         <span class="keywordflow">if</span> (ftruncate(fd, <span class="keyword">sizeof</span>(T)) &lt; 0) {
00583             ::close(fd);
00584             <span class="keywordflow">return</span> <span class="keyword">false</span>;
00585         }
00586         ptr = (T*)mmap(NULL,
00587                        DOALIGN(<span class="keyword">sizeof</span>(T), 4096),
00588                        PROT_READ|PROT_WRITE,
00589                        MAP_SHARED,
00590                        fd,
00591                        0);
00592         <span class="keywordflow">if</span> (ptr == MAP_FAILED) { 
00593             ptr = NULL;
00594             ::close(fd);
00595             <span class="keywordflow">return</span> <span class="keyword">false</span>;
00596         }
00597         <span class="keywordflow">return</span> <span class="keyword">true</span>;
00598     }
00599 
00600     T* get() { <span class="keywordflow">return</span> ptr; }
00601 
00602     <span class="keywordtype">void</span> close() { 
00603         <span class="keywordflow">if</span> (ptr != NULL) { 
00604             munmap(ptr, DOALIGN(<span class="keyword">sizeof</span>(T), 4096));
00605         }
00606         <span class="keywordflow">if</span> (fd &gt; 0) { 
00607             ::close(fd);
00608         }
00609     }
00610     <span class="keywordtype">void</span> erase() {
00611         close();
00612         unlink(name);   
00613     }  
00614 
00615     ~dbSharedObject() { 
00616         <span class="keyword">delete</span>[] name;
00617     }
00618 };
00619 
00620 <span class="preprocessor">#else // USE_POSIX_MMAP</span>
00621 <span class="preprocessor"></span>
00622 <span class="comment">// Non POSIX, internal implementations of SharedMemory and SharedObject</span>
00623 <span class="keyword">extern</span> <span class="keywordtype">char</span> <span class="keyword">const</span>* keyFileDir; <span class="comment">// default value: "/tmp/" </span>
00624 <span class="keyword">class </span>dbSharedMemory { 
00625   <span class="keyword">protected</span>:
00626     <span class="keywordtype">char</span>*  ptr;
00627     <span class="keywordtype">int</span>    shm;
00628 
00629   <span class="keyword">public</span>:
00630     <span class="keywordtype">bool</span>  open(<span class="keywordtype">char</span> <span class="keyword">const</span>* name, size_t size); 
00631     <span class="keywordtype">void</span>  close();
00632     <span class="keywordtype">void</span>  erase(); 
00633     <span class="keywordtype">char</span>* get_base() { 
00634         <span class="keywordflow">return</span> ptr;
00635     }
00636 };
00637 
00638 <span class="keyword">template</span>&lt;<span class="keyword">class</span> T&gt;
00639 <span class="keyword">class </span>dbSharedObject : <span class="keyword">public</span> dbSharedMemory { 
00640   <span class="keyword">public</span>:
00641     <span class="keywordtype">bool</span> open(<span class="keywordtype">char</span>* name) { 
00642         <span class="keywordflow">return</span> dbSharedMemory::open(name, <span class="keyword">sizeof</span>(T));
00643     }
00644     T* get() { <span class="keywordflow">return</span> (T*)ptr; }
00645 };
00646 
00647 <span class="preprocessor">#endif</span>
00648 <span class="preprocessor"></span>
00650 <span class="comment">// Define dBGlobalCriticalSection for various platforms</span>
00651 
00652 <span class="comment">// QNX uses a pthread based mutex for its implementation</span>
00653 <span class="comment">//     Use only if pthread support is also enabled, else we'll use the default case</span>
00654 <span class="preprocessor">#if defined(__QNX__) &amp;&amp; !defined(NO_PTHREADS)</span>
00655 <span class="preprocessor"></span><span class="keyword">typedef</span> pthread_mutex_t sharedsem_t;
00656 
00657 <span class="keyword">class </span>dbGlobalCriticalSection { 
00658     pthread_mutexattr_t attr;
00659     sharedsem_t* sem;
00660   <span class="keyword">public</span>:
00661     <span class="keywordtype">void</span> enter() {
00662         <span class="keywordtype">int</span> rc = pthread_mutex_lock(sem);
00663         assert(rc == 0);
00664     }
00665     <span class="keywordtype">void</span> leave() { 
00666         <span class="keywordtype">int</span> rc = pthread_mutex_unlock(sem);
00667         assert(rc == 0);
00668     }
00669     <span class="keywordtype">bool</span> open(<span class="keywordtype">char</span> <span class="keyword">const</span>*, sharedsem_t* shr) { 
00670         sem = shr;
00671         <span class="keywordflow">return</span> <span class="keyword">true</span>;
00672     }
00673     <span class="keywordtype">bool</span> create(<span class="keywordtype">char</span> <span class="keyword">const</span>*, sharedsem_t* shr) { 
00674         sem = shr;
00675         pthread_mutexattr_init(&amp;attr);
00676         pthread_mutexattr_setpshared(&amp;attr, PTHREAD_PROCESS_SHARED);
00677         pthread_mutexattr_setrecursive(&amp;attr, PTHREAD_RECURSIVE_ENABLE);
00678         pthread_mutex_init(sem, &amp;attr);
00679         <span class="keywordflow">return</span> <span class="keyword">true</span>;
00680     }
00681     <span class="keywordtype">void</span> close() {}
00682     <span class="keywordtype">void</span> erase() {
00683         pthread_mutex_destroy(sem);
00684     }
00685 };
00686 
00687 
00688 <span class="preprocessor">#elif defined(__osf__)</span>
00689 <span class="preprocessor"></span><span class="comment">// OSF uses "shared memory semaphores", located within a region mapped with mmap().</span>
00690 <span class="comment">// XXX: Perhaps Konstantin can give some insight why this method was chosen</span>
00691 <span class="preprocessor">#include &lt;errno.h&gt;</span>
00692 <span class="keyword">typedef</span> msemaphore sharedsem_t;
00693 
00694 <span class="keyword">class </span>dbGlobalCriticalSection { 
00695     sharedsem_t* sem;
00696   <span class="keyword">public</span>:
00697     <span class="keywordtype">void</span> enter() { 
00698         <span class="keywordtype">int</span> rc;
00699         <span class="keywordflow">while</span> ((rc = msem_lock(sem, 0)) &lt; 0 &amp;&amp; errno == EINTR);
00700         assert(rc == 0);
00701     }
00702     <span class="keywordtype">void</span> leave() { 
00703         <span class="keywordtype">int</span> rc = msem_unlock(sem, 0);
00704         assert(rc == 0);        
00705     }
00706     <span class="keywordtype">bool</span> open(<span class="keywordtype">char</span> <span class="keyword">const</span>*, sharedsem_t* shr) { 
00707         sem = shr;
00708         <span class="keywordflow">return</span> <span class="keyword">true</span>;
00709     }
00710     <span class="keywordtype">bool</span> create(<span class="keywordtype">char</span> <span class="keyword">const</span>*, sharedsem_t* shr) { 
00711         sem = shr;
00712         msem_init(shr, MSEM_UNLOCKED);
00713         <span class="keywordflow">return</span> <span class="keyword">true</span>;
00714     }
00715     <span class="keywordtype">void</span> close() {}
00716     <span class="keywordtype">void</span> erase() {
00717         msem_remove(sem);
00718     }
00719 };
00720         
00721 
00722 <span class="preprocessor">#elif defined(__sun)</span>
00723 <span class="preprocessor"></span><span class="comment">// Sun uses the Solaris style semaphore implemenation (sema_init(), sema_post())</span>
00724 <span class="preprocessor">#include &lt;synch.h&gt;</span>
00725 <span class="preprocessor">#include &lt;errno.h&gt;</span>
00726 <span class="keyword">typedef</span> sema_t sharedsem_t;
00727 
00728 <span class="keyword">class </span>dbGlobalCriticalSection { 
00729     sharedsem_t* sem;
00730   <span class="keyword">public</span>:
00731     <span class="keywordtype">void</span> enter() { 
00732         <span class="keywordtype">int</span> rc;
00733         <span class="keywordflow">while</span> ((rc = sema_wait(sem)) &lt; 0 &amp;&amp; errno == EINTR);
00734         assert(rc == 0);
00735     }
00736     <span class="keywordtype">void</span> leave() { 
00737         <span class="keywordtype">int</span> rc = sema_post(sem);
00738         assert(rc == 0);
00739     }
00740     <span class="keywordtype">bool</span> open(<span class="keywordtype">char</span> <span class="keyword">const</span>*, sharedsem_t* shr) { 
00741         sem = shr;
00742         <span class="keywordflow">return</span> <span class="keyword">true</span>;
00743     }
00744     <span class="keywordtype">bool</span> create(<span class="keywordtype">char</span> <span class="keyword">const</span>*, sharedsem_t* shr) { 
00745         sem = shr;
00746         <span class="keywordflow">return</span> sema_init(shr, 1, USYNC_PROCESS, NULL) == 0;
00747     }
00748     <span class="keywordtype">void</span> close() {}
00749     <span class="keywordtype">void</span> erase() {
00750         sema_destroy(sem);
00751     }
00752 };
00753 
00754 <span class="preprocessor">#elif defined(USE_POSIX_SEMAPHORES)</span>
00755 <span class="preprocessor"></span><span class="comment">// Everyone else uses the POSIX style semaphores (sem_wait(), sem_post(), etc) if defined</span>
00756 <span class="keyword">typedef</span> sem_t sharedsem_t;
00757 
00758 <span class="keyword">class </span>dbGlobalCriticalSection { 
00759     sharedsem_t* sem;
00760 
00761   <span class="keyword">public</span>:
00762     <span class="keywordtype">void</span> enter() { 
00763         <span class="keywordtype">int</span> rc = sem_wait(sem);
00764         assert(rc == 0);
00765     }
00766     <span class="keywordtype">void</span> leave() { 
00767         <span class="keywordtype">int</span> rc = sem_post(sem);
00768         assert(rc == 0);
00769     }
00770     <span class="keywordtype">bool</span> open(<span class="keywordtype">char</span> <span class="keyword">const</span>* name, sharedsem_t* shr) { 
00771         sem = shr;
00772         <span class="keywordflow">return</span> <span class="keyword">true</span>;
00773     }
00774 
00775         <span class="comment">// XXX: BUG Check the sem_init() return</span>
00776     <span class="keywordtype">bool</span> create(<span class="keywordtype">char</span> <span class="keyword">const</span>* name, sharedsem_t* shr) {   
00777         sem = shr;
00778         <span class="keywordflow">return</span> sem_init(sem, 1, 1) == 0;
00779     }
00780     <span class="keywordtype">void</span> close() {}
00781     <span class="keywordtype">void</span> erase() { 
00782         sem_destroy(sem);
00783     }
00784 };
00785 
00786 <span class="preprocessor">#else</span>
00787 <span class="preprocessor"></span>
00788 <span class="preprocessor">#define USE_LOCAL_CS_IMPL</span>
00789 <span class="preprocessor"></span>
00790 <span class="comment">// Lastly, use the local implementation</span>
00791 <span class="keyword">typedef</span> <span class="keywordtype">long</span> sharedsem_t;
00792 
00793 <span class="keyword">class </span>dbGlobalCriticalSection { 
00794     <span class="keywordtype">int</span>          semid;
00795     sharedsem_t* count;
00796 
00797   <span class="keyword">public</span>:
00798     <span class="keywordtype">void</span> enter(); 
00799     <span class="keywordtype">void</span> leave();
00800     <span class="keywordtype">bool</span> open(<span class="keywordtype">char</span> <span class="keyword">const</span>* name, sharedsem_t* shr);
00801     <span class="keywordtype">bool</span> create(<span class="keywordtype">char</span> <span class="keyword">const</span>* name, sharedsem_t* shr);
00802     <span class="keywordtype">void</span> close() {}
00803     <span class="keywordtype">void</span> erase();
00804 };
00805 <span class="preprocessor">#endif //dbGLobalCriticalSection switch</span>
00806 <span class="preprocessor"></span>
00807 <span class="preprocessor">#endif //__SYNC_UNIX_H__</span>
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