Add support for the sqlite3_txn_state() interface.

FossilOrigin-Name: ad195e3dd89d0f33b50070c18fb8f43c4eb24162515dfdd7c04d9e7d96b902a2

manifest

@@ -1,5 +1,5 @@
-C Reduce\sthe\sN\sin\sthe\slogN\sterm\sfor\sthe\ssorting\scost\sassociated\swith\scomputing\nDISTINCT\sby\sB-Tree\sby\shalf,\sunder\sthe\sassumption\sthat\sthe\sDISTINCT\swill\neliminate\sabout\shalf\sthe\srows\sof\soutput.\s\sThis\sis\sreally\sa\swild\sguess.\s\sBut\nwe\sdo\snot\shave\sany\sbetter\sway\sof\sestimating\swhat\sthe\srow-count\sreduction\sdue\nto\sDISTINCT\swill\sactually\sbe.
+C Add\ssupport\sfor\sthe\ssqlite3_txn_state()\sinterface.
-D 2020-08-24T23:44:27.235
+D 2020-08-25T19:09:07.606
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -471,14 +471,14 @@ F sqlite3.1 fc7ad8990fc8409983309bb80de8c811a7506786
 F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
 F src/alter.c 805de23ddca536181f8f0439df989fdd4a2f76c40bc305ec9fe2f211f68c89e8
 F src/analyze.c 5cffff3d355858cd22bfc6e20ac7203510d2e1cc935086eb06f4abb2f579f628
-F src/attach.c 0b11e00c166b622c84ec176773b1d691c61ad07d247809e3e1635d4e99e71d30
+F src/attach.c 0f497c15c4cfe3bdcb214f0dbdbbb6c5ed7e8a9308ac445c7959f5e5780437a9
 F src/auth.c a3d5bfdba83d25abed1013a8c7a5f204e2e29b0c25242a56bc02bb0c07bf1e06
-F src/backup.c b1c90cd4110248c8e1273ff4578d3a84c0c34725e1b96dacd4a6294a908702de
+F src/backup.c 3014889fa06e20e6adfa0d07b60097eec1f6e5b06671625f476a714d2356513d
 F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c 1439fd9b45d4d1883c53752daef42af489adaa1a1508fa39dedbc9c80ea21a2f
+F src/btree.c 634381c86f363dfd470c9dbe64c07363e746cb9917573f67381c861b1d264d8d
-F src/btree.h 7af72bbb4863c331c8f6753277ab40ee67d2a2125a63256d5c25489722ec162b
+F src/btree.h c299ab8b279230de1ef457f298ade9848c7339de6ef88a55beaf62bf0345eb15
-F src/btreeInt.h 83166f6daeb91062b6ae9ee6247b3ad07e40eba58f3c05ba9e8dedad4ab1ea38
+F src/btreeInt.h d1f713b2947a054c3532154a4d6b2bb8c4698fb54432f171966bdd06728ab1be
 F src/build.c a80bc79f0be20185e2005b74e9a23f8abb8fbb3cc54ed769a21865f79d507d90
 F src/callback.c d0b853dd413255d2e337b34545e54d888ea02f20da5ad0e63585b389624c4a6c
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
@@ -499,7 +499,7 @@ F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c 1103270dfc1a94d1ca69f36dc3e021a335459583195e4b9e5a4d6e3c840279ba
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 436af4968c6954d304fce9efa12719367bd8f37b19b93b71d6ad607e85adbb47
-F src/main.c 09580279145f27f3db206ef44dcb3a8875a42644230f79c7e54aff35e71668f0
+F src/main.c d71b989398a4cdb4e7ece0478b763834d7732fb78dd24702d36366743853ac82
 F src/malloc.c 22d5bdd9fe88ae4fad1b91a1b9735104b82853ffef868f1f05517d60dc1875f5
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
@@ -528,16 +528,16 @@ F src/parse.y 5bdb760a29c0b25caf7e80e82210b81cd2ea3066d5199ca29e6eac40b34bc184
 F src/pcache.c 385ff064bca69789d199a98e2169445dc16e4291fa807babd61d4890c3b34177
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
 F src/pcache1.c 6596e10baf3d8f84cc1585d226cf1ab26564a5f5caf85a15757a281ff977d51a
-F src/pragma.c bdb600be936f66b9fe69d26dfbba4528beaaf4f95c479c85b328a92484e0bf71
+F src/pragma.c 5435b9fe17f7728bd460f52d6d9388e7e45658c6f5549f28fc2d408be9efd2d5
 F src/pragma.h 8dc78ab7e9ec6ce3ded8332810a2066f1ef6267e2e03cd7356ee00276125c6cf
-F src/prepare.c 3d5a761d026052bc888d1b803a06dd2bfe245e8e836d4689f927003549148b0f
+F src/prepare.c 38ae9c2e3550bfa496886a862a5344c420ded052fd92294f409a07a53f372ffe
 F src/printf.c 9efcd4e984f22bcccb1ded37a1178cac98f6e3a0534e1e0629f64899971f8838
 F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
 F src/resolve.c 97b91fb25d86881ff20c9ad2ad98412c6c1bb5f7d6c9bb044db250cbc9cfcd4b
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
 F src/select.c 233e884d7da6601486c7b93aedb97fd29302ae5c03742d0e0eccb4790638bb77
 F src/shell.c.in b6d5d6ebeb8903e4946f23f0886f24133e0a9b6ecbc4cf90ede422ba297e73d5
-F src/sqlite.h.in d2c03414a8ee5d4a6855c04dd7cd5998e45139b0fe66b65bae86d4223edd091f
+F src/sqlite.h.in b91e4a5b9b25eb95260be0bf9716d2bdba0da06b72eb439f41592b226f58881d
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 2d1af80082edffd71c6f96f70ad1ce6a4fb46615ad10291fc77fe0dea9ff0197
 F src/sqliteInt.h 7dd1f3a93e801c90cf108149d041c6cc32d3e9503d66aa415455dae1614b6b53
@@ -545,7 +545,7 @@ F src/sqliteLimit.h d7323ffea5208c6af2734574bae933ca8ed2ab728083caa117c9738581a3
 F src/status.c 4b8bc2a6905163a38b739854a35b826c737333fab5b1f8e03fa7eb9a4799c4c1
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
 F src/tclsqlite.c 986b6391f02cd9b53c1d688be55899f6ffddeb8e8014cd83c1b73ff912579a71
-F src/test1.c 24b9cd0863ecc4d3920f4999c40e876c2bd92f3cc5879c48b99abe02c546ed18
+F src/test1.c 9e52fb797bf74fa327295df38881aa3ade0824bfb0c14abd0719e555b169fd55
 F src/test2.c 3efb99ab7f1fc8d154933e02ae1378bac9637da5
 F src/test3.c 61798bb0d38b915067a8c8e03f5a534b431181f802659a6616f9b4ff7d872644
 F src/test4.c 7c4420e01c577b5c4add2cb03119743b1a357543d347773b9e717195ea967159
@@ -606,12 +606,12 @@ F src/update.c 55a6203008d033fc1a9c125d7a0a61efdb79bbb2e6db427b917d1d427b4639be
 F src/upsert.c 2920de71b20f04fe25eb00b655d086f0ba60ea133c59d7fa3325c49838818e78
 F src/utf.c ee39565f0843775cc2c81135751ddd93eceb91a673ea2c57f61c76f288b041a0
 F src/util.c c8bf30c4356b091bcc3b624d0e24b2b4d11b8be4d6c90d8e0705971e15cc819b
-F src/vacuum.c 1c4f8e2f39d950037f4cf946b6858c993d3a54c3101f78e05c76460a073afcf0
+F src/vacuum.c 492422c1463c076473bae1858799c7a0a5fe87a133d1223239447c422cd26286
-F src/vdbe.c e9f7f818f128c8600058c0eabb6b3975974c95153a104d340f419adabbc15b9f
+F src/vdbe.c e88c94a53f571b6cdc67a8dbdc2ac49ddb3c5b2435aad72d68612b2464728faa
 F src/vdbe.h 83603854bfa5851af601fc0947671eb260f4363e62e960e8a994fb9bbcd2aaa1
 F src/vdbeInt.h 762abffb7709f19c2cb74af1bba73a900f762e64f80d69c31c9ae89ed1066b60
 F src/vdbeapi.c c5e7cb2ab89a24d7f723e87b508f21bfb1359a04db5277d8a99fd1e015c12eb9
-F src/vdbeaux.c 73854da7a9a4f12db72a855758214173c82f46a14be6cb19e63677ba02c97cae
+F src/vdbeaux.c b39d2e0e7126cd4629874dd7b67162b9f0d200b620d2b4c16d400949a2f1094b
 F src/vdbeblob.c 253ed82894924c362a7fa3079551d3554cd1cdace39aa833da77d3bc67e7c1b1
 F src/vdbemem.c 947f2a65910edb4014dc981d33e414a68c51f169f9df8c4c493a0ba840b6eb1f
 F src/vdbesort.c 2be76d26998ce2b3324cdcc9f6443728e54b6c7677c553ad909c7d7cfab587df
@@ -1588,7 +1588,7 @@ F test/tpch01.test 7c4eb8cdd79c568f46d344b3e789c9fdb8a766d112871352704861f3fca32
 F test/trace.test a659a9862957f4789e37a92b3bf6d2caf5c86b02cdeefc41e850ae53acf6992a
 F test/trace2.test f5cb67ad3bc09e0c58e8cca78dfd0b5639259983
 F test/trace3.test 1dff966888773ff1bfea01c080caf15417892b3f998408fe920c4791f7337144
-F test/trans.test 6e1b4c6a42dba31bd65f8fa5e61a2708e08ddde6
+F test/trans.test 45f6f9ab6f66a7b5744f1caac06b558f95da62501916906cf55586a896f9f439
 F test/trans2.test 62bd045bfc7a1c14c5ba83ba64d21ade31583f76
 F test/trans3.test 91a100e5412b488e22a655fe423a14c26403ab94
 F test/transitive1.test 293300f46916569f08875cdb2fe2134be2c27677
@@ -1879,7 +1879,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 493a25949b9a6d0be82169b597133e491d8be4f4147b6eae135b06c1d810abd3
+P 8787417ec1da8071d84c6ff0d7a90b5fd458ab6baba871327f36bc4e1bceca61
-R ddd62187ac7223d5e6ce61819bf672f8
+R 722b615829cb4461022a7ec168b6d94f
 U drh
-Z 3f2dc6629d15095497f0f8f6b9a935ba
+Z af427d9ac0f51142694fe72fc2db903f

manifest.uuid

@@ -1 +1 @@
-8787417ec1da8071d84c6ff0d7a90b5fd458ab6baba871327f36bc4e1bceca61
+ad195e3dd89d0f33b50070c18fb8f43c4eb24162515dfdd7c04d9e7d96b902a2

src/attach.c

@@ -293,7 +293,9 @@ static void detachFunc(
     sqlite3_snprintf(sizeof(zErr),zErr, "cannot detach database %s", zName);
     goto detach_error;
   }
-  if( sqlite3BtreeIsInReadTrans(pDb->pBt) || sqlite3BtreeIsInBackup(pDb->pBt) ){
+  if( sqlite3BtreeTxnState(pDb->pBt)!=SQLITE_TXN_NONE
+   || sqlite3BtreeIsInBackup(pDb->pBt)
+  ){
     sqlite3_snprintf(sizeof(zErr),zErr, "database %s is locked", zName);
     goto detach_error;
   }

src/backup.c

@@ -123,7 +123,7 @@ static int setDestPgsz(sqlite3_backup *p){
 ** message in database handle db.
 */
 static int checkReadTransaction(sqlite3 *db, Btree *p){
-  if( sqlite3BtreeIsInReadTrans(p) ){
+  if( sqlite3BtreeTxnState(p)!=SQLITE_TXN_NONE ){
     sqlite3ErrorWithMsg(db, SQLITE_ERROR, "destination database is in use");
     return SQLITE_ERROR;
   }
@@ -354,7 +354,7 @@ int sqlite3_backup_step(sqlite3_backup *p, int nPage){
     ** one now. If a transaction is opened here, then it will be closed
     ** before this function exits.
     */
-    if( rc==SQLITE_OK && 0==sqlite3BtreeIsInReadTrans(p->pSrc) ){
+    if( rc==SQLITE_OK && SQLITE_TXN_NONE==sqlite3BtreeTxnState(p->pSrc) ){
       rc = sqlite3BtreeBeginTrans(p->pSrc, 0, 0);
       bCloseTrans = 1;
     }
@@ -726,7 +726,7 @@ int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
   sqlite3BtreeEnter(pTo);
   sqlite3BtreeEnter(pFrom);
 
-  assert( sqlite3BtreeIsInTrans(pTo) );
+  assert( sqlite3BtreeTxnState(pTo)==SQLITE_TXN_WRITE );
   pFd = sqlite3PagerFile(sqlite3BtreePager(pTo));
   if( pFd->pMethods ){
     i64 nByte = sqlite3BtreeGetPageSize(pFrom)*(i64)sqlite3BtreeLastPage(pFrom);
@@ -762,7 +762,7 @@ int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
     sqlite3PagerClearCache(sqlite3BtreePager(b.pDest));
   }
 
-  assert( sqlite3BtreeIsInTrans(pTo)==0 );
+  assert( sqlite3BtreeTxnState(pTo)!=SQLITE_TXN_WRITE );
 copy_finished:
   sqlite3BtreeLeave(pFrom);
   sqlite3BtreeLeave(pTo);

src/btree.c

@@ -10310,11 +10310,12 @@ const char *sqlite3BtreeGetJournalname(Btree *p){
 }
 
 /*
-** Return non-zero if a transaction is active.
+** Return one of SQLITE_TXN_NONE, SQLITE_TXN_READ, or SQLITE_TXN_WRITE
+** to describe the current transaction state of Btree p.
 */
-int sqlite3BtreeIsInTrans(Btree *p){
+int sqlite3BtreeTxnState(Btree *p){
   assert( p==0 || sqlite3_mutex_held(p->db->mutex) );
-  return (p && (p->inTrans==TRANS_WRITE));
+  return p ? p->inTrans : 0;
 }
 
 #ifndef SQLITE_OMIT_WAL
@@ -10343,14 +10344,8 @@ int sqlite3BtreeCheckpoint(Btree *p, int eMode, int *pnLog, int *pnCkpt){
 #endif
 
 /*
-** Return non-zero if a read (or write) transaction is active.
+** Return true if there is currently a backup running on Btree p.
 */
-int sqlite3BtreeIsInReadTrans(Btree *p){
-  assert( p );
-  assert( sqlite3_mutex_held(p->db->mutex) );
-  return p->inTrans!=TRANS_NONE;
-}
-
 int sqlite3BtreeIsInBackup(Btree *p){
   assert( p );
   assert( sqlite3_mutex_held(p->db->mutex) );

src/btree.h

@@ -85,8 +85,7 @@ int sqlite3BtreeCommit(Btree*);
 int sqlite3BtreeRollback(Btree*,int,int);
 int sqlite3BtreeBeginStmt(Btree*,int);
 int sqlite3BtreeCreateTable(Btree*, Pgno*, int flags);
-int sqlite3BtreeIsInTrans(Btree*);
+int sqlite3BtreeTxnState(Btree*);
-int sqlite3BtreeIsInReadTrans(Btree*);
 int sqlite3BtreeIsInBackup(Btree*);
 void *sqlite3BtreeSchema(Btree *, int, void(*)(void *));
 int sqlite3BtreeSchemaLocked(Btree *pBtree);

src/btreeInt.h

@@ -364,11 +364,25 @@ struct Btree {
 ** If the shared-data extension is enabled, there may be multiple users
 ** of the Btree structure. At most one of these may open a write transaction,
 ** but any number may have active read transactions.
+**
+** These values must match SQLITE_TXN_NONE, SQLITE_TXN_READ, and
+** SQLITE_TXN_WRITE
 */
 #define TRANS_NONE  0
 #define TRANS_READ  1
 #define TRANS_WRITE 2
 
+#if TRANS_NONE!=SQLITE_TXN_NONE
+# error wrong numeric code for no-transaction
+#endif
+#if TRANS_READ!=SQLITE_TXN_READ
+# error wrong numeric code for read-transaction
+#endif
+#if TRANS_WRITE!=SQLITE_TXN_WRITE
+# error wrong numeric code for write-transaction
+#endif
+
+
 /*
 ** An instance of this object represents a single database file.
 ** 

src/main.c

@@ -897,7 +897,7 @@ int sqlite3_db_cacheflush(sqlite3 *db){
   sqlite3BtreeEnterAll(db);
   for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
     Btree *pBt = db->aDb[i].pBt;
-    if( pBt && sqlite3BtreeIsInTrans(pBt) ){
+    if( pBt && sqlite3BtreeTxnState(pBt)==SQLITE_TXN_WRITE ){
       Pager *pPager = sqlite3BtreePager(pBt);
       rc = sqlite3PagerFlush(pPager);
       if( rc==SQLITE_BUSY ){
@@ -1241,6 +1241,36 @@ static int sqlite3Close(sqlite3 *db, int forceZombie){
   return SQLITE_OK;
 }
 
+/*
+** Return the transaction state for a single databse, or the maximum
+** transaction state over all attached databases if zSchema is null.
+*/
+int sqlite3_txn_state(sqlite3 *db, const char *zSchema){
+  int iDb, nDb;
+  int iTxn = -1;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) ){
+    (void)SQLITE_MISUSE_BKPT;
+    return -1;
+  }
+#endif
+  sqlite3_mutex_enter(db->mutex);
+  if( zSchema ){
+    nDb = iDb = sqlite3FindDbName(db, zSchema);
+    if( iDb<0 ) nDb--;
+  }else{
+    iDb = 0;
+    nDb = db->nDb-1;
+  }
+  for(; iDb<=nDb; iDb++){
+    Btree *pBt = db->aDb[iDb].pBt;
+    int x = pBt!=0 ? sqlite3BtreeTxnState(pBt) : SQLITE_TXN_NONE;
+    if( x>iTxn ) iTxn = x;
+  }
+  sqlite3_mutex_leave(db->mutex);
+  return iTxn;
+}
+
 /*
 ** Two variations on the public interface for closing a database
 ** connection. The sqlite3_close() version returns SQLITE_BUSY and
@@ -1401,7 +1431,7 @@ void sqlite3RollbackAll(sqlite3 *db, int tripCode){
   for(i=0; i<db->nDb; i++){
     Btree *p = db->aDb[i].pBt;
     if( p ){
-      if( sqlite3BtreeIsInTrans(p) ){
+      if( sqlite3BtreeTxnState(p)==SQLITE_TXN_WRITE ){
         inTrans = 1;
       }
       sqlite3BtreeRollback(p, tripCode, !schemaChange);
@@ -4440,7 +4470,7 @@ int sqlite3_snapshot_get(
     int iDb = sqlite3FindDbName(db, zDb);
     if( iDb==0 || iDb>1 ){
       Btree *pBt = db->aDb[iDb].pBt;
-      if( 0==sqlite3BtreeIsInTrans(pBt) ){
+      if( SQLITE_TXN_WRITE!=sqlite3BtreeTxnState(pBt) ){
         rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
         if( rc==SQLITE_OK ){
           rc = sqlite3PagerSnapshotGet(sqlite3BtreePager(pBt), ppSnapshot);
@@ -4476,10 +4506,10 @@ int sqlite3_snapshot_open(
     iDb = sqlite3FindDbName(db, zDb);
     if( iDb==0 || iDb>1 ){
       Btree *pBt = db->aDb[iDb].pBt;
-      if( sqlite3BtreeIsInTrans(pBt)==0 ){
+      if( sqlite3BtreeTxnState(pBt)!=SQLITE_TXN_WRITE ){
         Pager *pPager = sqlite3BtreePager(pBt);
         int bUnlock = 0;
-        if( sqlite3BtreeIsInReadTrans(pBt) ){
+        if( sqlite3BtreeTxnState(pBt)!=SQLITE_TXN_NONE ){
           if( db->nVdbeActive==0 ){
             rc = sqlite3PagerSnapshotCheck(pPager, pSnapshot);
             if( rc==SQLITE_OK ){
@@ -4528,7 +4558,7 @@ int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb){
   iDb = sqlite3FindDbName(db, zDb);
   if( iDb==0 || iDb>1 ){
     Btree *pBt = db->aDb[iDb].pBt;
-    if( 0==sqlite3BtreeIsInReadTrans(pBt) ){
+    if( SQLITE_TXN_NONE==sqlite3BtreeTxnState(pBt) ){
       rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
       if( rc==SQLITE_OK ){
         rc = sqlite3PagerSnapshotRecover(sqlite3BtreePager(pBt));

src/pragma.c

@@ -131,7 +131,9 @@ static int getTempStore(const char *z){
 static int invalidateTempStorage(Parse *pParse){
   sqlite3 *db = pParse->db;
   if( db->aDb[1].pBt!=0 ){
-    if( !db->autoCommit || sqlite3BtreeIsInReadTrans(db->aDb[1].pBt) ){
+    if( !db->autoCommit
+     || sqlite3BtreeTxnState(db->aDb[1].pBt)!=SQLITE_TXN_NONE
+    ){
       sqlite3ErrorMsg(pParse, "temporary storage cannot be changed "
         "from within a transaction");
       return SQLITE_ERROR;

src/prepare.c

@@ -240,7 +240,7 @@ int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg, u32 mFlags){
   ** on the b-tree database, open one now. If a transaction is opened, it 
   ** will be closed before this function returns.  */
   sqlite3BtreeEnter(pDb->pBt);
-  if( !sqlite3BtreeIsInReadTrans(pDb->pBt) ){
+  if( sqlite3BtreeTxnState(pDb->pBt)==SQLITE_TXN_NONE ){
     rc = sqlite3BtreeBeginTrans(pDb->pBt, 0, 0);
     if( rc!=SQLITE_OK ){
       sqlite3SetString(pzErrMsg, db, sqlite3ErrStr(rc));
@@ -483,7 +483,7 @@ static void schemaIsValid(Parse *pParse){
     /* If there is not already a read-only (or read-write) transaction opened
     ** on the b-tree database, open one now. If a transaction is opened, it 
     ** will be closed immediately after reading the meta-value. */
-    if( !sqlite3BtreeIsInReadTrans(pBt) ){
+    if( sqlite3BtreeTxnState(pBt)==SQLITE_TXN_NONE ){
       rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
       if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
         sqlite3OomFault(db);

src/sqlite.h.in

@@ -6186,6 +6186,57 @@ const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
 */
 int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
 
+/*
+** CAPI3REF: Determine the transaction state of a database
+** METHOD: sqlite3
+**
+** ^The sqlite3_txn_state(D,S) interface returns the current
+** [transaction state] of schema S in database connection D.  ^If S is NULL,
+** then the highest transaction state of any schema on databse connection D
+** is returned.  Transaction states are (in order of lowest to highest):
+** <ol>
+** <li value="0"> SQLITE_TXN_NONE
+** <li value="1"> SQLITE_TXN_READ
+** <li value="2"> SQLITE_TXN_WRITE
+** </ol>
+** ^If the S argument to sqlite3_txn_state(D,S) is in the name of
+** a valid schema, then -1 is returned.
+*/
+int sqlite3_txn_state(sqlite3*,const char *zSchema);
+
+/*
+** CAPI3REF: Allowed return values from [sqlite3_txn_state()]
+** KEYWORDS: {transaction state}
+**
+** These constants define the current transaction state of a database file.
+** ^The [sqlite3_txn_state(D,S)] interface returns one of these
+** constants in order to describe the transaction state of schema S
+** in [database connection] D.
+**
+** <dl>
+** [[SQLITE_TXN_NONE]] <dt>SQLITE_TXN_NONE</dt>
+** <dd>The SQLITE_TXN_NONE state means that no transaction is currently
+** pending.</dd>
+**
+** [[SQLITE_TXN_READ]] <dt>SQLITE_TXN_READ</dt>
+** <dd>The SQLITE_TXN_READ state means that the database is currently
+** in a read transaction.  Content has been read from the database file
+** but nothing in the database file has changed.  The transaction state
+** will advanced to SQLITE_TXN_WRITE if any changes occur and there are
+** no other conflicting concurrent write transactions.  The transaction
+** state will revert to SQLITE_TXN_NONE following a [ROLLBACK] or
+** [COMMIT].</dd>
+**
+** [[SQLITE_TXN_WRITE]] <dt>SQLITE_TXN_WRITE</dt>
+** <dd>The SQLITE_TXN_WRITE state means that the database is currently
+** in a write transaction.  Content has been written to the database file
+** but has not yet committed.  The transaction state will change to
+** to SQLITE_TXN_NONE at the next [ROLLBACK] or [COMMIT].</dd>
+*/
+#define SQLITE_TXN_NONE  0
+#define SQLITE_TXN_READ  1
+#define SQLITE_TXN_WRITE 2
+
 /*
 ** CAPI3REF: Find the next prepared statement
 ** METHOD: sqlite3
@@ -9345,6 +9396,7 @@ void sqlite3_stmt_scanstatus_reset(sqlite3_stmt*);
 
 /*
 ** CAPI3REF: Flush caches to disk mid-transaction
+** METHOD: sqlite3
 **
 ** ^If a write-transaction is open on [database connection] D when the
 ** [sqlite3_db_cacheflush(D)] interface invoked, any dirty
@@ -9377,6 +9429,7 @@ int sqlite3_db_cacheflush(sqlite3*);
 
 /*
 ** CAPI3REF: The pre-update hook.
+** METHOD: sqlite3
 **
 ** ^These interfaces are only available if SQLite is compiled using the
 ** [SQLITE_ENABLE_PREUPDATE_HOOK] compile-time option.
@@ -9479,6 +9532,7 @@ int sqlite3_preupdate_new(sqlite3 *, int, sqlite3_value **);
 
 /*
 ** CAPI3REF: Low-level system error code
+** METHOD: sqlite3
 **
 ** ^Attempt to return the underlying operating system error code or error
 ** number that caused the most recent I/O error or failure to open a file.

src/test1.c

@@ -7749,6 +7749,33 @@ static int SQLITE_TCLAPI test_sqlite3_db_config(
   Tcl_SetObjResult(interp, Tcl_NewIntObj(v));
   return TCL_OK;
 }
+/*
+** tclcmd:   sqlite3_txn_state DB ?SCHEMA?
+**
+** Invoke sqlite3_txn_state(DB,SCHEMA) and return the
+** numeric value that results.  Use NULL for SCHEMA if the 3 argument
+** is omitted.
+*/
+static int SQLITE_TCLAPI test_sqlite3_txn_state(
+  void *clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+  sqlite3 *db;
+  const char *zSchema;
+  int iTxn;
+
+  if( objc!=2 && objc!=3 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "DB ?SCHEMA?");
+    return TCL_ERROR;
+  }
+  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
+  zSchema = objc==3 ? Tcl_GetString(objv[2]) : 0;
+  iTxn = sqlite3_txn_state(db, zSchema);
+  Tcl_SetObjResult(interp, Tcl_NewIntObj(iTxn));
+  return TCL_OK;
+}
 
 /*
 ** Change the name of the main database schema from "main" to "icecube".
@@ -7985,6 +8012,7 @@ int Sqlitetest1_Init(Tcl_Interp *interp){
      void *clientData;
   } aObjCmd[] = {
      { "sqlite3_db_config",             test_sqlite3_db_config, 0 },
+     { "sqlite3_txn_state",             test_sqlite3_txn_state, 0 },
      { "bad_behavior",                  test_bad_behavior,  (void*)&iZero },
      { "register_dbstat_vtab",          test_register_dbstat_vtab  },
      { "sqlite3_connection_pointer",    get_sqlite_pointer, 0 },

src/vacuum.c

@@ -339,8 +339,8 @@ SQLITE_NOINLINE int sqlite3RunVacuum(
        BTREE_APPLICATION_ID,     0,  /* Preserve the application id */
     };
 
-    assert( 1==sqlite3BtreeIsInTrans(pTemp) );
+    assert( SQLITE_TXN_WRITE==sqlite3BtreeTxnState(pTemp) );
-    assert( pOut!=0 || 1==sqlite3BtreeIsInTrans(pMain) );
+    assert( pOut!=0 || SQLITE_TXN_WRITE==sqlite3BtreeTxnState(pMain) );
 
     /* Copy Btree meta values */
     for(i=0; i<ArraySize(aCopy); i+=2){

src/vdbe.c

@@ -3546,7 +3546,7 @@ case OP_Transaction: {
      && pOp->p2
      && (db->autoCommit==0 || db->nVdbeRead>1) 
     ){
-      assert( sqlite3BtreeIsInTrans(pBt) );
+      assert( sqlite3BtreeTxnState(pBt)==SQLITE_TXN_WRITE );
       if( p->iStatement==0 ){
         assert( db->nStatement>=0 && db->nSavepoint>=0 );
         db->nStatement++; 
@@ -7038,7 +7038,7 @@ case OP_JournalMode: {    /* out2 */
       /* Open a transaction on the database file. Regardless of the journal
       ** mode, this transaction always uses a rollback journal.
       */
-      assert( sqlite3BtreeIsInTrans(pBt)==0 );
+      assert( sqlite3BtreeTxnState(pBt)!=SQLITE_TXN_WRITE );
       if( rc==SQLITE_OK ){
         rc = sqlite3BtreeSetVersion(pBt, (eNew==PAGER_JOURNALMODE_WAL ? 2 : 1));
       }

src/vdbeaux.c

@@ -2663,7 +2663,7 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
   */ 
   for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
     Btree *pBt = db->aDb[i].pBt;
-    if( sqlite3BtreeIsInTrans(pBt) ){
+    if( sqlite3BtreeTxnState(pBt)==SQLITE_TXN_WRITE ){
       /* Whether or not a database might need a super-journal depends upon
       ** its journal mode (among other things).  This matrix determines which
       ** journal modes use a super-journal and which do not */
@@ -2798,7 +2798,7 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
     */
     for(i=0; i<db->nDb; i++){
       Btree *pBt = db->aDb[i].pBt;
-      if( sqlite3BtreeIsInTrans(pBt) ){
+      if( sqlite3BtreeTxnState(pBt)==SQLITE_TXN_WRITE ){
         char const *zFile = sqlite3BtreeGetJournalname(pBt);
         if( zFile==0 ){
           continue;  /* Ignore TEMP and :memory: databases */

test/trans.test

@@ -11,7 +11,6 @@
 # This file implements regression tests for SQLite library.  The
 # focus of this script is database locks.
 #
-# $Id: trans.test,v 1.41 2009/04/28 16:37:59 danielk1977 Exp $
 
 
 set testdir [file dirname $argv0]
@@ -39,6 +38,19 @@ do_test trans-1.1 {
     SELECT b FROM two ORDER BY a;
   }
 } {I V X}
+do_test trans-1.2.1 {
+  sqlite3_txn_state db
+} {0}
+do_test trans-1.2.2 {
+  sqlite3_txn_state db main
+} {0}
+do_test trans-1.2.3 {
+  sqlite3_txn_state db temp
+} {0}
+do_test trans-1.2.4 {
+  sqlite3_txn_state db no-such-schema
+} {-1}
+
 do_test trans-1.9 {
   sqlite3 altdb test.db
   execsql {SELECT b FROM one ORDER BY a} altdb
@@ -55,6 +67,9 @@ do_test trans-2.1 {
   set v [catch {execsql {BEGIN}} msg]
   lappend v $msg
 } {0 {}}
+do_test trans-2.1b {
+  sqlite3_txn_state db
+} {0}
 do_test trans-2.2 {
   set v [catch {execsql {END}} msg]
   lappend v $msg
@@ -95,6 +110,16 @@ do_test trans-3.1 {
     SELECT a FROM one ORDER BY a;
   }
 } {1 2 3}
+do_test trans-3.1b {
+  sqlite3_txn_state db
+} {2}
+do_test trans-3.1c {
+  sqlite3_txn_state db main
+} {2}
+do_test trans-3.1d {
+  sqlite3_txn_state db temp
+} {0}
+
 do_test trans-3.2 {
   catchsql {
     SELECT a FROM two ORDER BY a;
@@ -139,6 +164,10 @@ do_test trans-3.9 {
 do_test trans-3.10 {
   execsql {END TRANSACTION}
 } {}
+do_test trans-3.10b {
+  sqlite3_txn_state db
+} {0}
+
 
 do_test trans-3.11 {
   set v [catch {execsql {
@@ -252,6 +281,15 @@ do_test trans-5.2 {
   execsql {BEGIN TRANSACTION}
   execsql {SELECT name FROM sqlite_master WHERE type='table' ORDER BY name}
 } {}
+do_test trans-5.2b {
+  sqlite3_txn_state db
+} {1}
+do_test trans-5.2c {
+  sqlite3_txn_state db main
+} {1}
+do_test trans-5.2d {
+  sqlite3_txn_state db temp
+} {0}
 do_test trans-5.3 {
   execsql {CREATE TABLE one(a text, b int)}
   execsql {SELECT name FROM sqlite_master WHERE type='table' ORDER BY name}