From: dan <dan@noemail.net>
Date: Sat, 19 Aug 2017 15:50:45 +0000 (+0000)
Subject: Ensure that write-locks on pages are dropped at the end of each
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7c4805fa5c33e6b79b7d781c6c0620a4629ee5ae;p=thirdparty%2Fsqlite.git

Ensure that write-locks on pages are dropped at the end of each
write transaction, even if there is still a read transaction open.

FossilOrigin-Name: 2dd36ade9ea948de27b217b83cbf704e071e6ea5dddb8566165a645143b0f846
---

diff --git a/manifest b/manifest
index b1acfb1482..7737c83668 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\stests\sto\sthis\sbranch.
-D 2017-08-18T18:55:22.047
+C Ensure\sthat\swrite-locks\son\spages\sare\sdropped\sat\sthe\send\sof\seach\nwrite\stransaction,\seven\sif\sthere\sis\sstill\sa\sread\stransaction\sopen.
+D 2017-08-19T15:50:45.975
 F Makefile.in d9873c9925917cca9990ee24be17eb9613a668012c85a343aef7e5536ae266e8
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 02b469e9dcd5b7ee63fc1fb05babc174260ee4cfa4e0ef2e48c3c6801567a016
@@ -442,7 +442,7 @@ F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
 F src/os_unix.c 6947c0fccc1b68404def7161553881b2efab6fcac4a58bf9f4ce36a4ad27d325
 F src/os_win.c 964165b66cde03abc72fe948198b01be608436894732eadb94c8720d2467f223
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
-F src/pager.c e53f35d61f266c47cc3883e34c7d01eaca38a71451dd72efb3cf21e043b471a7
+F src/pager.c 4e8dc5bf9011a2a26e3ab18838f3c07d82e5d56c5bf177c5c11bfd63cdc2f429
 F src/pager.h 316dac0671fd7555af9e73d4357febd5f2d3ce6a185ffd8d77b7fc0423ac8b1a
 F src/parse.y 58a2de13e855aece3d7709440e6e86849f4cde97f5227c6a25e6bba2fc5e2976
 F src/pcache.c 62835bed959e2914edd26afadfecce29ece0e870
@@ -456,8 +456,8 @@ F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
 F src/resolve.c 4324a94573b1e29286f8121e4881db59eaedc014afeb274c8d3e07ed282e0e20
 F src/rowset.c 7b7e7e479212e65b723bf40128c7b36dc5afdfac
 F src/select.c c9b3d8444bbf6f167d84f41ca6f3672e2521cb163a8c706b19058dc82fffe9b8
-F src/server.c 6ed43d130950389006399268ce3e9a8b1951eefc3709a5730e24b026712500b0
-F src/server.h cf1ede28aaa07a30550228582f211327b5ebe5517d2334e35ec09d00fd6d230d
+F src/server.c 4215bc2287c28f37e2bc79521eb8163e1340be2ca45f0fe4b2566f5faec9300c
+F src/server.h f46be129ffe407cac9b7018e6d4851b04e685d59b6837c73a1fb69e6aab52e3a
 F src/shell.c bd6a37cbe8bf64ef6a6a74fdc50f067d3148149b4ce2b4d03154663e66ded55f
 F src/shell.c.in b5725acacba95ccefa57b6d068f710e29ba8239c3aa704628a1902a1f729c175
 F src/sqlite.h.in 29317515594eb3db2800a21fe8b568e502d76899fc64cc3b685f90c4a1ebe214
@@ -1171,13 +1171,13 @@ F test/selectE.test a8730ca330fcf40ace158f134f4fe0eb00c7edbf
 F test/selectF.test 21c94e6438f76537b72532fa9fd4710cdd455fc3
 F test/selectG.test e8600e379589e85e9fefd2fe4d44a4cdd63f6982
 F test/server1.test 46803bd3fe8b99b30dbc5ff38ffc756f5c13a118
-F test/server2.test e7890fb1eb9a11a0f94cd0892279e0f3cd1ba8c3006fa343637ee9ff3c4689f6
+F test/server2.test 787ba6044b5e9b2c3d60588bc5596054e6a5c3a7dc64bc2fb0e62f6616c142a9
 F test/server3.test c3ae4ca7a6e7df870bfcd2450a9815507eaa80b9cdc44ee6c7975d48311505d4
 F test/server_common.tcl c491d0f509b94a5cca845d45ca3bb47e464ad3a4bc89641982269112d0f1f3f4
 F test/servercrash.test 1cbd2f98cadee2d8d42ed85ad76fbcf48958fedd537c82221838cd9bc6899dae
-F test/serverfreelist.test 2e554001145170094a19731a8ce2981d040cf44c947542b35d130e6e31256fca w test/server5.test
+F test/serverfreelist.test 2e554001145170094a19731a8ce2981d040cf44c947542b35d130e6e31256fca
 F test/serverlimit.test 4bc013c0b991956486ddbff6ea3bee78a0d14a3d8091f5ec00e2bd34a7fa9aa7
-F test/serverreadonly.test 97040670597948a695b1973537d770417589f1998bcbb3959302aaee3c211250 w test/server4.test
+F test/serverreadonly.test 97040670597948a695b1973537d770417589f1998bcbb3959302aaee3c211250
 F test/session.test 78fa2365e93d3663a6e933f86e7afc395adf18be
 F test/shared.test 1da9dbad400cee0d93f252ccf76e1ae007a63746
 F test/shared2.test 03eb4a8d372e290107d34b6ce1809919a698e879
@@ -1658,7 +1658,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 66fb9e1cb479f1e764f1606f041bd97fd3bd428093832c000ee36b643377e9e2
-R 6a3c43c16b1d75fce7516d061ebaa6d6
+P abb6e076c851c0b10f62c02d0d7e54f24d86c75f01036dddbc0a8a7dfc627a0d
+R aa6e06e084e3c3d3595864687ba9477a
 U dan
-Z f1a62abc260e8d42c995536e20991d87
+Z 571fa6db3e131de25960c3e8f380a0b4
diff --git a/manifest.uuid b/manifest.uuid
index 74095647dd..a55ffa5f42 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-abb6e076c851c0b10f62c02d0d7e54f24d86c75f01036dddbc0a8a7dfc627a0d
\ No newline at end of file
+2dd36ade9ea948de27b217b83cbf704e071e6ea5dddb8566165a645143b0f846
\ No newline at end of file
diff --git a/src/pager.c b/src/pager.c
index 00bceddcf8..218a61ebe3 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -2159,7 +2159,7 @@ static int pager_end_transaction(Pager *pPager, int hasMaster, int bCommit){
 
 #ifdef SQLITE_SERVER_EDITION
   if( pagerIsServer(pPager) ){
-    rc2 = sqlite3ServerReleaseWriteLocks(pPager->pServer);
+    rc2 = sqlite3ServerEndWrite(pPager->pServer);
   }else
 #endif
   if( !pPager->exclusiveMode 
diff --git a/src/server.c b/src/server.c
index f42ee4de81..f72e7a9dc9 100644
--- a/src/server.c
+++ b/src/server.c
@@ -623,45 +623,17 @@ static void serverReleaseLocks(Server *p){
   p->nLock = 0;
 }
 
-/*
-** End a transaction (and release all locks). This version runs in
-** single process mode only.
-*/
-static void serverEndSingle(Server *p){
-  Server **pp;
-  ServerDb *pDb = p->pDb;
-  ServerPage *pPg = 0;
-
-  assert( p->eTrans!=SERVER_TRANS_NONE );
+static void serverRecycleBuffers(ServerDb *pDb){
   assert( pDb->pServerShm==0 );
-
-  sqlite3_mutex_enter(pDb->mutex);
-
-  if( p->eTrans==SERVER_TRANS_READONLY ){
-    /* Remove the connection from the readers list */
-    for(pp=&pDb->pReader; *pp!=p; pp = &((*pp)->pNext));
-    *pp = p->pNext;
-  }else{
-    serverReleaseLocks(p);
-
-    /* Clear the bit in the transaction mask. */
-    pDb->transmask &= ~((u32)1 << p->iTransId);
-
-    /* If this connection is in the committers list, remove it. */
-    for(pp=&pDb->pCommit; *pp; pp = &((*pp)->pNext)){
-      if( *pp==p ){
-        *pp = p->pNext;
-        break;
-      }
-    }
-  }
+  assert( sqlite3_mutex_held(pDb->mutex) );
 
   /* See if it is possible to free any ServerPage records. If so, remove
-  ** them from the linked list and hash table, but do not call sqlite3_free()
-  ** on them until the mutex has been released.  */
+  ** them from the linked list and hash table, and add them to the pFree
+  ** list.  */
   if( pDb->pPgFirst ){
-    ServerPage *pLast = 0;
+    ServerPage *pPg;
     Server *pIter;
+    ServerPage *pLast = 0;
     int iOldest = 0x7FFFFFFF;
     for(pIter=pDb->pReader; pIter; pIter=pIter->pNext){
       iOldest = MIN(iOldest, pIter->iCommitId);
@@ -696,12 +668,37 @@ static void serverEndSingle(Server *p){
       pDb->pPgFirst = pPg;
     }
   }
+}
+
+/*
+** End a transaction (and release all locks). This version runs in
+** single process mode only.
+*/
+static void serverEndSingle(Server *p){
+  Server **pp;
+  ServerDb *pDb = p->pDb;
+
+  assert( p->eTrans!=SERVER_TRANS_NONE );
+  assert( pDb->pServerShm==0 );
 
+  sqlite3_mutex_enter(pDb->mutex);
+
+  if( p->eTrans==SERVER_TRANS_READONLY ){
+    /* Remove the connection from the readers list */
+    for(pp=&pDb->pReader; *pp!=p; pp = &((*pp)->pNext));
+    *pp = p->pNext;
+  }else{
+    serverReleaseLocks(p);
+
+    /* Clear the bit in the transaction mask. */
+    pDb->transmask &= ~((u32)1 << p->iTransId);
+  }
+
+  serverRecycleBuffers(pDb);
   sqlite3_mutex_leave(pDb->mutex);
 
   p->pNext = 0;
   p->iTransId = -1;
-  p->iCommitId = 0;
 }
 
 /*
@@ -786,9 +783,37 @@ int sqlite3ServerPreCommit(Server *p, ServerPage *pPg){
 /*
 ** Release all write-locks.
 */
-int sqlite3ServerReleaseWriteLocks(Server *p){
-  int rc = SQLITE_OK;
-  return rc;
+int sqlite3ServerEndWrite(Server *p){
+  ServerDb *pDb = p->pDb;
+  int i;
+
+  if( pDb->pServerShm==0 ) sqlite3_mutex_enter(pDb->mutex);
+  for(i=0; i<p->nLock; i++){
+    while( 1 ){
+      u32 *pSlot = serverLockingSlot(pDb, p->aLock[i]);
+      u32 o = *pSlot;
+      u32 n = o & ~((u32)1 << p->iTransId);
+      if( slotGetWriter(n)==p->iTransId ){
+        n -= ((p->iTransId + 1) << HMA_MAX_TRANSACTIONID);
+        n |= ((u32)1 << p->iTransId);
+      }
+      if( o==n || serverCompareAndSwap(pSlot, o, n) ) break;
+    }
+  }
+  if( pDb->pServerShm==0 ){
+    ServerDb **pp;
+    /* If this connection is in the committers list, remove it. */
+    for(pp=&pDb->pCommit; *pp; pp = &((*pp)->pNext)){
+      if( *pp==p ){
+        *pp = p->pNext;
+        break;
+      }
+    }
+    p->iCommitId = 0;
+    sqlite3_mutex_leave(pDb->mutex);
+  }
+
+  return SQLITE_OK;
 }
 
 static int serverCheckClient(Server *p, int iClient){
@@ -898,11 +923,6 @@ int sqlite3ServerLock(Server *p, Pgno pgno, int bWrite, int bBlock){
   return rc;
 }
 
-int sqlite3ServerHasLock(Server *p, Pgno pgno, int bWrite){
-  assert( 0 );
-  return 0;
-}
-
 static void serverIncrSlowReader(u32 *pSlot, int n){
   assert( n==1 || n==-1 );
   *pSlot += (n * (1 << HMA_SLOT_RLWL_BITS));
diff --git a/src/server.h b/src/server.h
index 17fdc8ce81..85e9cbb049 100644
--- a/src/server.h
+++ b/src/server.h
@@ -38,12 +38,10 @@ int sqlite3ServerBegin(Server *p, int bReadonly);
 int sqlite3ServerPreCommit(Server*, ServerPage*);
 int sqlite3ServerEnd(Server *p);
 
-int sqlite3ServerReleaseWriteLocks(Server *p);
+int sqlite3ServerEndWrite(Server *p);
 
 int sqlite3ServerLock(Server *p, Pgno pgno, int bWrite, int bBlock);
 
-int sqlite3ServerHasLock(Server *p, Pgno pgno, int bWrite);
-
 ServerPage *sqlite3ServerBuffer(Server*);
 
 int sqlite3ServerIsSingleProcess(Server*);
diff --git a/test/server2.test b/test/server2.test
index d0888369d1..809364d9f1 100644
--- a/test/server2.test
+++ b/test/server2.test
@@ -142,6 +142,33 @@ foreach {tn vfs} {1 unix-excl 2 unix} {
     db close
     lsort [glob -nocomplain test.db-journal/*-journal]
   } {}
+
+  #-----------------------------------------------------------------------
+  # Test that write-locks are downgraded when a transaction is ended,
+  # even if the connection holds an open read statement.
+  #
+  do_test $tn.4.1 {
+    server_sqlite3 db test.db
+    server_sqlite3 db2 test.db
+    db eval {
+      CREATE TABLE t2(a);
+      INSERT INTO t2 VALUES('one');
+      INSERT INTO t2 VALUES('two');
+      INSERT INTO t2 VALUES('three');
+      CREATE TABLE t3(k INTEGER PRIMARY KEY, val);
+    }
+
+    set res [list]
+    db eval { SELECT a FROM t2 ORDER BY rowid } {
+      db eval { REPLACE INTO t3 VALUES(1, $a) }
+      lappend res [db2 one { SELECT val FROM t3 }]
+    }
+
+    set res
+  } {one two three}
+
+  catch { db close }
+  catch { db2 close }
 }
 
 finish_test