From a111165bab37e74bcaa76b1ba6182549a785361d Mon Sep 17 00:00:00 2001

From: Mark Reynolds <mreynolds@redhat.com>

Date: Wed, 20 Nov 2013 09:08:50 -0500

Subject: [PATCH 57/65] Ticket 47599 - Reduce lock scope in retro changelog

 plug-in

Description:  Use RW locks for protecting the change numbers.

              We still need to do the locking in retrocl_po.c as we need to

              serialize the actual updates.

https://fedorahosted.org/389/ticket/47599

Reviewed by: richm(Thanks!!)

(cherry picked from commit e2c42bced86bac235ac56ae98eed303f61ebd15e)

(cherry picked from commit 03f6347eb72d3cbb49ae33312f32df9f91a2fd4c)

---

 ldap/servers/plugins/retrocl/retrocl.c    |  3 ++-

 ldap/servers/plugins/retrocl/retrocl.h    |  1 +

 ldap/servers/plugins/retrocl/retrocl_cn.c | 42 +++++++++++++++++++++----------

 ldap/servers/plugins/retrocl/retrocl_po.c |  2 +-

 4 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/ldap/servers/plugins/retrocl/retrocl.c b/ldap/servers/plugins/retrocl/retrocl.c

index 90c3455..3e426a7 100644

--- a/ldap/servers/plugins/retrocl/retrocl.c

+++ b/ldap/servers/plugins/retrocl/retrocl.c

@@ -465,7 +465,8 @@ retrocl_plugin_init(Slapi_PBlock *pb)

 	  if (!is_betxn) {

 	    rc= slapi_register_plugin_ext("internalpostoperation", 1 /* Enabled */, "retrocl_internalpostop_init", retrocl_internalpostop_init, "Retrocl internal postoperation plugin", NULL, identity, precedence);

 	  }

-

+	  retrocl_cn_lock = slapi_new_rwlock();

+	  if(retrocl_cn_lock == NULL) return -1;

 	  retrocl_internal_lock = PR_NewLock();

 	  if (retrocl_internal_lock == NULL) return -1;

 	}

diff --git a/ldap/servers/plugins/retrocl/retrocl.h b/ldap/servers/plugins/retrocl/retrocl.h

index 276912b..bfebe2e 100644

--- a/ldap/servers/plugins/retrocl/retrocl.h

+++ b/ldap/servers/plugins/retrocl/retrocl.h

@@ -130,6 +130,7 @@ extern const char *attr_nsuniqueid;

 extern const char *attr_isreplicated;

 extern PRLock *retrocl_internal_lock;

+extern Slapi_RWLock *retrocl_cn_lock;

 /* Functions */

diff --git a/ldap/servers/plugins/retrocl/retrocl_cn.c b/ldap/servers/plugins/retrocl/retrocl_cn.c

index d2b15a4..f816730 100644

--- a/ldap/servers/plugins/retrocl/retrocl_cn.c

+++ b/ldap/servers/plugins/retrocl/retrocl_cn.c

@@ -163,8 +163,9 @@ int retrocl_get_changenumbers(void)

 		       NULL,NULL,0,&cr,NULL,handle_cnum_result,

 		       handle_cnum_entry, NULL);

-    retrocl_first_cn = cr.cr_cnum;

+    slapi_rwlock_wrlock(retrocl_cn_lock);

+    retrocl_first_cn = cr.cr_cnum;

     slapi_ch_free(( void **) &cr.cr_time );

     slapi_seq_callback(RETROCL_CHANGELOG_DN,SLAPI_SEQ_LAST,

@@ -178,6 +179,8 @@ int retrocl_get_changenumbers(void)

 		    retrocl_first_cn,

 		    retrocl_internal_cn);

+    slapi_rwlock_unlock(retrocl_cn_lock);

+

     slapi_ch_free(( void **) &cr.cr_time );

     return 0;

@@ -238,10 +241,10 @@ time_t retrocl_getchangetime( int type, int *err )

 void retrocl_forget_changenumbers(void) 

 { 

-    PR_Lock(retrocl_internal_lock);

+    slapi_rwlock_wrlock(retrocl_cn_lock);

     retrocl_first_cn = 0;

     retrocl_internal_cn = 0;

-    PR_Unlock(retrocl_internal_lock);

+    slapi_rwlock_unlock(retrocl_cn_lock);

 }

 /*

@@ -258,9 +261,11 @@ void retrocl_forget_changenumbers(void)

 changeNumber retrocl_get_first_changenumber(void) 

 { 

     changeNumber cn;

-    PR_Lock(retrocl_internal_lock);

+

+    slapi_rwlock_rdlock(retrocl_cn_lock);

     cn = retrocl_first_cn;

-    PR_Unlock(retrocl_internal_lock);

+    slapi_rwlock_unlock(retrocl_cn_lock);

+

     return cn;

 }

@@ -277,9 +282,9 @@ changeNumber retrocl_get_first_changenumber(void)

 void retrocl_set_first_changenumber(changeNumber cn) 

 { 

-    PR_Lock(retrocl_internal_lock);

+    slapi_rwlock_wrlock(retrocl_cn_lock);

     retrocl_first_cn = cn;

-    PR_Unlock(retrocl_internal_lock);

+    slapi_rwlock_unlock(retrocl_cn_lock);

 }

@@ -297,9 +302,11 @@ void retrocl_set_first_changenumber(changeNumber cn)

 changeNumber retrocl_get_last_changenumber(void) 

 { 

     changeNumber cn;

-    PR_Lock(retrocl_internal_lock);

+

+    slapi_rwlock_rdlock(retrocl_cn_lock);

     cn = retrocl_internal_cn;

-    PR_Unlock(retrocl_internal_lock);

+    slapi_rwlock_unlock(retrocl_cn_lock);

+

     return cn;

 }

@@ -316,9 +323,11 @@ changeNumber retrocl_get_last_changenumber(void)

 void retrocl_commit_changenumber(void) 

 { 

+    slapi_rwlock_wrlock(retrocl_cn_lock);

     if ( retrocl_first_cn == 0) {

         retrocl_first_cn = retrocl_internal_cn;

     }

+    slapi_rwlock_unlock(retrocl_cn_lock);

 }

 /*

@@ -333,8 +342,10 @@ void retrocl_commit_changenumber(void)

  */

 void retrocl_release_changenumber(void) 

-{ 

+{

+    slapi_rwlock_wrlock(retrocl_cn_lock);

     retrocl_internal_cn--;

+    slapi_rwlock_unlock(retrocl_cn_lock);

 }

 /*

@@ -342,7 +353,7 @@ void retrocl_release_changenumber(void)

  *

  * Returns: 0/-1

  *

- * Arguments: none

+ * Arguments: none.  The caller should have taken write lock for the change numbers

  *

  * Description: reads the last entry in the changelog to obtain

  * the last change number.

@@ -355,6 +366,7 @@ int retrocl_update_lastchangenumber(void)

     if (retrocl_be_changelog == NULL) return -1;

+    slapi_rwlock_unlock(retrocl_cn_lock);

     cr.cr_cnum = 0;

     cr.cr_time = 0;

     slapi_seq_callback(RETROCL_CHANGELOG_DN,SLAPI_SEQ_LAST,

@@ -362,7 +374,7 @@ int retrocl_update_lastchangenumber(void)

                NULL,NULL,0,&cr,NULL,handle_cnum_result,

                handle_cnum_entry, NULL);

-

+    slapi_rwlock_wrlock(retrocl_cn_lock);

     retrocl_internal_cn = cr.cr_cnum;

     slapi_log_error(SLAPI_LOG_PLUGIN,"retrocl","Refetched last changenumber =  %lu \n",

             retrocl_internal_cn);

@@ -394,6 +406,8 @@ changeNumber retrocl_assign_changenumber(void)

      * validity of the internal assignment of retrocl_internal_cn 

      * we had from the startup */  

+    slapi_rwlock_wrlock(retrocl_cn_lock);

+

     if(retrocl_internal_cn <= retrocl_first_cn){ 

         /* the numbers have become out of sync - retrocl_get_changenumbers

          * gets called only once during startup and it may have had a problem 

@@ -404,8 +418,10 @@ changeNumber retrocl_assign_changenumber(void)

          */                                                         

         retrocl_update_lastchangenumber();                                   

     }                             

-

     retrocl_internal_cn++;

     cn = retrocl_internal_cn;

+

+    slapi_rwlock_unlock(retrocl_cn_lock);

+

     return cn;

 }

diff --git a/ldap/servers/plugins/retrocl/retrocl_po.c b/ldap/servers/plugins/retrocl/retrocl_po.c

index 382c98a..cd290f2 100644

--- a/ldap/servers/plugins/retrocl/retrocl_po.c

+++ b/ldap/servers/plugins/retrocl/retrocl_po.c

@@ -372,7 +372,7 @@ write_replog_db(

 	    retrocl_release_changenumber();

 	} else {

 	/* Tell the change numbering system this one's committed to disk  */

-	    retrocl_commit_changenumber( );

+	    retrocl_commit_changenumber();

 	}

     } else {

 	slapi_log_error( SLAPI_LOG_FATAL, RETROCL_PLUGIN_NAME, 

-- 

1.8.1.4