X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;f=util%2Fflock.c;h=98a1590fdb533a4adcac6cfc176d3fd7daaa3396;hb=11edef8271df7f3598f94373720aea3a5b6b3ad5;hp=5956832e59dea6e6ef396f3a514783510f1d259c;hpb=b374ab328be4535cff9412e265a3fb87c53c1272;p=idzebra-moved-to-github.git

diff --git a/util/flock.c b/util/flock.c
index 5956832..98a1590 100644
--- a/util/flock.c
+++ b/util/flock.c
@@ -1,4 +1,4 @@
-/* $Id: flock.c,v 1.10 2006-06-30 11:10:17 adam Exp $
+/* $Id: flock.c,v 1.16 2006-07-03 13:40:58 adam Exp $
    Copyright (C) 1995-2006
    Index Data ApS
 
@@ -40,13 +40,15 @@ Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include <yaz/xmalloc.h>
 #include <yaz/log.h>
 
+/** whether this module should debug */
 #define DEBUG_FLOCK 1
 
-#define ALWAYS_FLOCK 1
-
 /** have this module (mutex) been initialized? */
 static int initialized = 0;
 
+/** whether fcntl locks are shared for all threads in a process (POSIX) */
+static int posix_locks = 1;
+
 /** mutex for lock_list below */
 Zebra_mutex lock_list_mutex;
 
@@ -124,13 +126,17 @@ ZebraLockHandle zebra_lock_create(const char *dir, const char *name)
     assert(initialized);
 
     zebra_mutex_lock(&lock_list_mutex);
-#ifndef WIN32 
-    for (p = lock_list; p ; p = p->next)
-        if (!strcmp(p->fname, fname))
-            break;
+    /* see if we have the same filename in a global list of "lock files" */
+#ifndef WIN32
+    if (posix_locks)
+    {
+        for (p = lock_list; p ; p = p->next)
+            if (!strcmp(p->fname, fname))
+                break;
+    }
 #endif
     if (!p)
-    {
+    {   /* didn't match (or we didn't want it to match! */
         p = (struct zebra_lock_info *) xmalloc(sizeof(*p));
         
         p->ref_count = 0;
@@ -153,7 +159,9 @@ ZebraLockHandle zebra_lock_create(const char *dir, const char *name)
             p->fname = fname;
             fname = 0;  /* fname buffer now owned by p->fname */
 #ifndef WIN32
-            zebra_lock_rdwr_init(&p->rdwr_lock);
+            if (posix_locks)
+                zebra_lock_rdwr_init(&p->rdwr_lock);
+
             zebra_mutex_init(&p->file_mutex);
             p->no_file_write_lock = 0;
             p->no_file_read_lock = 0;
@@ -164,6 +172,7 @@ ZebraLockHandle zebra_lock_create(const char *dir, const char *name)
     }
     if (p)
     {
+        /* we have lock info so we can make a handle pointing to that */
         p->ref_count++;
         h = (ZebraLockHandle) xmalloc(sizeof(*h));
         h->p = p;
@@ -192,9 +201,8 @@ void zebra_lock_destroy(ZebraLockHandle h)
     --(h->p->ref_count);
     if (h->p->ref_count == 0)
     {
+        /* must remove shared info from lock_list */
         struct zebra_lock_info **hp = &lock_list;
-        yaz_log(log_level, "zebra_lock_destroy fd=%d p=%p fname=%s remove",
-                h->p->fd, h, h->p->fname);
         while (*hp)
         {
             if (*hp == h->p)
@@ -205,8 +213,13 @@ void zebra_lock_destroy(ZebraLockHandle h)
             else
                 hp = &(*hp)->next;
         }
+
+        yaz_log(log_level, "zebra_lock_destroy fd=%d p=%p fname=%s remove",
+                h->p->fd, h, h->p->fname);
+
 #ifndef WIN32
-        zebra_lock_rdwr_destroy(&h->p->rdwr_lock);
+        if (posix_locks)
+            zebra_lock_rdwr_destroy(&h->p->rdwr_lock);
         zebra_mutex_destroy(&h->p->file_mutex);
 #endif
         if (h->p->fd != -1)
@@ -241,34 +254,36 @@ static int unixLock(int fd, int type, int cmd)
 int zebra_lock_w(ZebraLockHandle h)
 {
     int r;
-    int do_lock = ALWAYS_FLOCK;
+    int do_lock = 0;
     yaz_log(log_level, "zebra_lock_w fd=%d p=%p fname=%s begin", 
             h->p->fd, h, h->p->fname);
-    
+
 #ifdef WIN32
     while ((r = _locking(h->p->fd, _LK_LOCK, 1)))
         ;
 #else
+    if (posix_locks)
+        zebra_lock_rdwr_wlock(&h->p->rdwr_lock);
+
     zebra_mutex_lock(&h->p->file_mutex);
     if (h->p->no_file_write_lock == 0)
         do_lock = 1;
     h->p->no_file_write_lock++;
-    zebra_mutex_unlock(&h->p->file_mutex);
     if (do_lock)
     {
-        yaz_log(log_level, "zebra_lock_w fd=%d p=%p fname=%s 2", 
-                h->p->fd, h, h->p->fname);
         /* if there is already a read lock.. upgrade to write lock */
         r = unixLock(h->p->fd, F_WRLCK, F_SETLKW);
     }
-    yaz_log(log_level, "zebra_lock_w fd=%d p=%p fname=%s 3", 
-            h->p->fd, h, h->p->fname);
+    else
+    {
+        assert(posix_locks);
+    }
+    zebra_mutex_unlock(&h->p->file_mutex);
 
-    zebra_lock_rdwr_wlock(&h->p->rdwr_lock);
     h->write_flag = 1;
+#endif
     yaz_log(log_level, "zebra_lock_w fd=%d p=%p fname=%s end", 
             h->p->fd, h, h->p->fname);
-#endif
 
     return r;
 }
@@ -276,77 +291,119 @@ int zebra_lock_w(ZebraLockHandle h)
 int zebra_lock_r(ZebraLockHandle h)
 {
     int r;
-    int do_lock = ALWAYS_FLOCK;
+    int do_lock = 0;
 
-    yaz_log(log_level, "zebra_lock_r fd=%d p=%p fname=%s", 
+    yaz_log(log_level, "zebra_lock_r fd=%d p=%p fname=%s begin", 
             h->p->fd, h, h->p->fname);
 #ifdef WIN32
     while ((r = _locking(h->p->fd, _LK_LOCK, 1)))
         ;
 #else
+    if (posix_locks)
+        zebra_lock_rdwr_rlock(&h->p->rdwr_lock);
+
     zebra_mutex_lock(&h->p->file_mutex);
     if (h->p->no_file_read_lock == 0 && h->p->no_file_write_lock == 0)
         do_lock = 1;
     h->p->no_file_read_lock++;
-    zebra_mutex_unlock(&h->p->file_mutex);
-    
     if (do_lock)
     {
         /* only read lock if no write locks already */
         r = unixLock(h->p->fd, F_RDLCK, F_SETLKW);
     }
-
-    zebra_lock_rdwr_rlock(&h->p->rdwr_lock);
+    else
+    {
+        assert(posix_locks);
+    }
+    zebra_mutex_unlock(&h->p->file_mutex);
+    
     h->write_flag = 0;
 #endif
+    yaz_log(log_level, "zebra_lock_r fd=%d p=%p fname=%s end", 
+            h->p->fd, h, h->p->fname);
     return r;
 }
 
 int zebra_unlock(ZebraLockHandle h)
 {
     int r = 0;
-    int do_unlock = ALWAYS_FLOCK;
+    int do_unlock = 0;
     yaz_log(log_level, "zebra_unlock fd=%d p=%p fname=%s begin",
             h->p->fd, h, h->p->fname);
 #ifdef WIN32
     r = _locking(h->p->fd, _LK_UNLCK, 1);
 #else
-    if (h->write_flag)
-        zebra_lock_rdwr_wunlock(&h->p->rdwr_lock);
-    else
-        zebra_lock_rdwr_runlock(&h->p->rdwr_lock);
-
     zebra_mutex_lock(&h->p->file_mutex);
     if (h->write_flag)
-        h->p->no_file_write_lock--;
+    {
+        if (h->p->no_file_write_lock > 0)
+            h->p->no_file_write_lock--;
+    }
     else
-        h->p->no_file_read_lock--;
-    if (h->p->no_file_read_lock == 0 && h->p->no_file_write_lock == 0)
     {
+        if (h->p->no_file_read_lock > 0)
+            h->p->no_file_read_lock--;
+    }
+    if (h->p->no_file_read_lock == 0 && h->p->no_file_write_lock == 0)
         do_unlock = 1;
-        yaz_log(log_level, "zebra_unlock fd=%d p=%p fname=%s 2",
-                h->p->fd, h, h->p->fname);
+    if (do_unlock)
+        r = unixLock(h->p->fd, F_UNLCK, F_SETLKW);
+    else
+    {
+        assert(posix_locks);
     }
     zebra_mutex_unlock(&h->p->file_mutex);
 
-    if (do_unlock)
-        r = unixLock(h->p->fd, F_UNLCK, F_SETLKW);
+    if (posix_locks)
+    {
+        if (h->write_flag)
+            zebra_lock_rdwr_wunlock(&h->p->rdwr_lock);
+        else
+            zebra_lock_rdwr_runlock(&h->p->rdwr_lock);
+    }
+#endif
     yaz_log(log_level, "zebra_unlock fd=%d p=%p fname=%s end",
             h->p->fd, h, h->p->fname);
-#endif
     return r;
 }
 
+/** \brief see if the fcntl locking is not POSIX 
+ *
+ * The default posix_locks=1 is assumed.. This function sets posix_locks
+ * to zero if linuxthreads is in use.
+ */
+static int check_for_linuxthreads()
+{
+#if __linux
+#ifdef _CS_GNU_LIBPTHREAD_VERSION
+    char conf_buf[512];
+    size_t r = confstr(_CS_GNU_LIBPTHREAD_VERSION, conf_buf, sizeof(conf_buf));
+    if (r == 0)
+    {
+        yaz_log(YLOG_WARN|YLOG_ERRNO, "confstr failed");
+        return -1;
+    }
+    if (strncmp(conf_buf, "linuxthreads", 12) == 0)
+        posix_locks = 0; /* Using linuxthreads.. */
+#else
+    posix_locks = 0; /* Old GLIBC on Linux. Assume linuxthreads */
+#endif
+#endif
+    return 0;
+}
+
 void zebra_flock_init()
 {
     if (!initialized)
     {
+        initialized = 1;
         log_level = yaz_log_module_level("flock");
 #if DEBUG_FLOCK
         log_level = YLOG_LOG|YLOG_FLUSH;
 #endif
-        initialized = 1;
+        check_for_linuxthreads();
         zebra_mutex_init(&lock_list_mutex);
+        yaz_log(log_level, "posix_locks: %d", posix_locks);
     }
     yaz_log(log_level, "zebra_flock_init");
 }