Add thread pool routines.

[openldap] / libraries / libldap_r / rdwr.c

diff --git a/libraries/libldap_r/rdwr.c b/libraries/libldap_r/rdwr.c
index 60e2a420b69da768127daef7d327b1addcc3c40f..e97fe7143ca6060c37c0ecf7a685a89d95712bb1 100644 (file)
--- a/libraries/libldap_r/rdwr.c
+++ b/libraries/libldap_r/rdwr.c
@@ -1,3 +1,4 @@
+/* $OpenLDAP$ */
 /*
 ** This is an improved implementation of Reader/Writer locks does
 ** not protect writers from starvation.  That is, if a writer is
@@ -6,24 +7,28 @@
 **
 ** Does not support cancellation nor does any status checking.
 */
-
-/********************************************************
- * Adapted from:
+/* Adapted from publically available examples for:
  *     "Programming with Posix Threads"
- *             by David R Butenhof
- *             Addison-Wesley 
- ********************************************************
+ *             by David R Butenhof, Addison-Wesley 
+ *             http://cseng.aw.com/bookpage.taf?ISBN=0-201-63392-2
  */
 
 #include "portable.h"
 
-#include <stdlib.h>
+#include <ac/stdlib.h>
 
 #include <ac/errno.h>
 #include <ac/string.h>
 
 #include "ldap_pvt_thread.h"
 
+/*
+ * implementations that provide their own compatible 
+ * reader/writer locks define LDAP_THREAD_HAVE_RDWR
+ * in ldap_pvt_thread.h
+ */
+#ifndef LDAP_THREAD_HAVE_RDWR
+
 int 
 ldap_pvt_thread_rdwr_init( ldap_pvt_thread_rdwr_t *rw )
 {
@@ -52,7 +57,7 @@ ldap_pvt_thread_rdwr_destroy( ldap_pvt_thread_rdwr_t *rw )
        ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex );
 
        /* active threads? */
-       if( rw->ltrw_r_active > 0 || rw->ltrw_w_active > 1) {
+       if( rw->ltrw_r_active > 0 || rw->ltrw_w_active > 0) {
                ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
                return LDAP_PVT_THREAD_EBUSY;
        }
@@ -84,7 +89,7 @@ int ldap_pvt_thread_rdwr_rlock( ldap_pvt_thread_rdwr_t *rw )
 
        ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex );
 
-       if( rw->ltrw_w_active > 1 ) {
+       if( rw->ltrw_w_active > 0 ) {
                /* writer is active */
 
                rw->ltrw_r_wait++;
@@ -92,7 +97,7 @@ int ldap_pvt_thread_rdwr_rlock( ldap_pvt_thread_rdwr_t *rw )
                do {
                        ldap_pvt_thread_cond_wait(
                                &rw->ltrw_read, &rw->ltrw_mutex );
-               } while( rw->ltrw_w_active > 1 );
+               } while( rw->ltrw_w_active > 0 );
 
                rw->ltrw_r_wait--;
        }
@@ -114,7 +119,7 @@ int ldap_pvt_thread_rdwr_rtrylock( ldap_pvt_thread_rdwr_t *rw )
 
        ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex );
 
-       if( rw->ltrw_w_active > 1) {
+       if( rw->ltrw_w_active > 0) {
                ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
                return LDAP_PVT_THREAD_EBUSY;
        }
@@ -221,7 +226,7 @@ int ldap_pvt_thread_rdwr_wunlock( ldap_pvt_thread_rdwr_t *rw )
        return 0;
 }
 
-#ifdef LDAP_DEBUG
+#ifdef LDAP_RDWR_DEBUG
 
 /* just for testing, 
  * return 0 if false, suitable for assert(ldap_pvt_thread_rdwr_Xchk(rdwr))
@@ -259,3 +264,5 @@ int ldap_pvt_thread_rdwr_active(ldap_pvt_thread_rdwr_t *rw)
 }
 
 #endif /* LDAP_DEBUG */
+
+#endif /* LDAP_THREAD_HAVE_RDWR */