In LSM, avoid calling the VFS xTestLock method to test for a lock that

conflicts with one held by the same process. The results of such a call are
considered undefined (since they are different under win32 and posix).

FossilOrigin-Name: a82a9bea624caf6b24d8e3f3c596817968b258f06e54288022f6df8226281057

ext/lsm1/lsm_shared.c

@@ -253,6 +253,8 @@ static void doDbDisconnect(lsm_db *pDb){
     rc = lsmShmLock(pDb, LSM_LOCK_DMS1, LSM_LOCK_EXCL, 1);
     if( rc==LSM_OK ){
 
+      lsmShmLock(pDb, LSM_LOCK_DMS2, LSM_LOCK_UNLOCK, 0);
+
       /* Try an exclusive lock on DMS2. If successful, this is the last
       ** connection to the database. In this case flush the contents of the
       ** in-memory tree to disk and write a checkpoint.  */
@@ -324,7 +326,6 @@ static void doDbDisconnect(lsm_db *pDb){
       pDb->iRwclient = -1;
     }
 
-    lsmShmLock(pDb, LSM_LOCK_DMS2, LSM_LOCK_UNLOCK, 0);
     lsmShmLock(pDb, LSM_LOCK_DMS1, LSM_LOCK_UNLOCK, 0);
   }
   pDb->pShmhdr = 0;
@@ -477,8 +478,15 @@ int lsmDbDatabaseConnect(
       }
 
       if( rc==LSM_OK && p->bMultiProc==0 ){
+        /* Hold an exclusive lock DMS1 while grabbing DMS2. This ensures
+        ** that any ongoing call to doDbDisconnect() (even one in another
+        ** process) is finished before proceeding.  */
         assert( p->bReadonly==0 );
-        rc = lsmEnvLock(pDb->pEnv, p->pFile, LSM_LOCK_DMS2, LSM_LOCK_EXCL);
+        rc = lsmEnvLock(pDb->pEnv, p->pFile, LSM_LOCK_DMS1, LSM_LOCK_EXCL);
+        if( rc==LSM_OK ){
+          rc = lsmEnvLock(pDb->pEnv, p->pFile, LSM_LOCK_DMS2, LSM_LOCK_EXCL);
+          lsmEnvLock(pDb->pEnv, p->pFile, LSM_LOCK_DMS1, LSM_LOCK_UNLOCK);
+        }
       }
 
       if( rc==LSM_OK ){
@@ -1747,7 +1755,10 @@ int lsmShmTestLock(
 
   lsmMutexEnter(db->pEnv, p->pClientMutex);
   for(pIter=p->pConn; pIter; pIter=pIter->pNext){
-    if( pIter!=db && (pIter->mLock & mask) ) break;
+    if( pIter!=db && (pIter->mLock & mask) ){
+      assert( pIter!=db );
+      break;
+    }
   }
 
   if( pIter ){

manifest

@@ -1,5 +1,5 @@
-C Add\sthe\s"--newlines"\soption\sto\sthe\s".dump"\scommand\sin\sthe\sshell\sto\sdisable\nthe\snewline\sescaping\smechanism.
-D 2017-07-10T18:04:41.835
+C In\sLSM,\savoid\scalling\sthe\sVFS\sxTestLock\smethod\sto\stest\sfor\sa\slock\sthat\nconflicts\swith\sone\sheld\sby\sthe\ssame\sprocess.\sThe\sresults\sof\ssuch\sa\scall\sare\nconsidered\sundefined\s(since\sthey\sare\sdifferent\sunder\swin32\sand\sposix).
+D 2017-07-10T18:33:41.229
 F Makefile.in 081e48dfe7f995d57ce1a88ddf4d2917b4349158648a6cd45b42beae30de3a12
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 20850e3e8d4d4791e0531955852d768eb06f24138214870d543abb1a47346fba
@@ -243,7 +243,7 @@ F ext/lsm1/lsm_log.c 8308714659b9fe4a995c239528520c57d26a03baf1d1c973967493a089a
 F ext/lsm1/lsm_main.c 15e73ccdafdd44ddeefc29e332079d88ba8f00c12c797b3c2b63d3171b5afce8
 F ext/lsm1/lsm_mem.c 4c51ea9fa285ee6e35301b33491642d071740a0a
 F ext/lsm1/lsm_mutex.c 378edf0a2b142b4f7640ee982df06d50b98788ea
-F ext/lsm1/lsm_shared.c 54cc3a5157c6abd77f7d3ae60708b9f7bf022b3c
+F ext/lsm1/lsm_shared.c 54185ae27b7580a959127c700459b3358e39723afce12b6281f2dfe408cb0efd
 F ext/lsm1/lsm_sorted.c 9bc5251a54a5cb24c2f003c10595fa81ffc7178c4f200c6b0f83d50a2272bb1d
 F ext/lsm1/lsm_str.c 65e361b488c87b10bf3e5c0070b14ffc602cf84f094880bece77bbf6678bca82
 F ext/lsm1/lsm_tree.c 53b657439e0fcb1117b0559ad3567ac417f81f2ed0fff9bab79948a00ea3cacb
@@ -1628,7 +1628,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P c4cb90487f34937605732c3959891075e2aabfb0bd05e55c44565d65867093ea
-R 6d35197f305c27266246f32d8a4834d8
-U drh
-Z a3a7e11cbaa224fa5a8714694bd756ab
+P bde431b1e332feaeb516dc46d180e2b2f42820c471feed7eda89452ada898dc9
+R 71f00994c33b502fb1928c2468689120
+U dan
+Z 83fb5bcc897af021df9d77183bfae0e8

manifest.uuid

@@ -1 +1 @@
-bde431b1e332feaeb516dc46d180e2b2f42820c471feed7eda89452ada898dc9
+a82a9bea624caf6b24d8e3f3c596817968b258f06e54288022f6df8226281057