In shared-cache mode, do not allow one connection to checkpoint a database while a second connection is reading or writing the same shared-cache.

FossilOrigin-Name: e75b52d156905ce16bedb94f65c01a4640bdfa75

src/btree.c

@@ -7848,6 +7848,29 @@ int sqlite3BtreeIsInTrans(Btree *p){
   return (p && (p->inTrans==TRANS_WRITE));
 }
 
+#ifndef SQLITE_OMIT_WAL
+/*
+** Run a checkpoint on the Btree passed as the first argument.
+**
+** Return SQLITE_LOCKED if this or any other connection has an open 
+** transaction on the shared-cache the argument Btree is connected to.
+*/
+int sqlite3BtreeCheckpoint(Btree *p){
+  int rc = SQLITE_OK;
+  if( p ){
+    BtShared *pBt = p->pBt;
+    sqlite3BtreeEnter(p);
+    if( pBt->inTransaction!=TRANS_NONE ){
+      rc = SQLITE_LOCKED;
+    }else{
+      rc = sqlite3PagerCheckpoint(pBt->pPager);
+    }
+    sqlite3BtreeLeave(p);
+  }
+  return rc;
+}
+#endif
+
 /*
 ** Return non-zero if a read (or write) transaction is active.
 */

src/btree.h

@@ -201,6 +201,10 @@ int sqlite3BtreeCursorInfo(BtCursor*, int*, int);
 void sqlite3BtreeCursorList(Btree*);
 #endif
 
+#ifndef SQLITE_OMIT_WAL
+  int sqlite3BtreeCheckpoint(Btree*);
+#endif
+
 /*
 ** If we are not using shared cache, then there is no need to
 ** use mutexes to access the BtShared structures.  So make the

src/main.c

@@ -1308,16 +1308,7 @@ int sqlite3Checkpoint(sqlite3 *db, int iDb){
 
   for(i=0; i<db->nDb && rc==SQLITE_OK; i++){
     if( i==iDb || iDb==SQLITE_MAX_ATTACHED ){
-      Btree *pBt = db->aDb[i].pBt;
-      if( pBt ){
-        if( sqlite3BtreeIsInReadTrans(pBt) ){
-          rc = SQLITE_LOCKED;
-        }else{
-          sqlite3BtreeEnter(pBt);
-          rc = sqlite3PagerCheckpoint(sqlite3BtreePager(pBt));
-          sqlite3BtreeLeave(pBt);
-        }
-      }
+      rc = sqlite3BtreeCheckpoint(db->aDb[i].pBt);
     }
   }