Merge pull request #1852 from tursodatabase/fix-disappearing-frames

libsql-sqlite3: Fix problem with disappearing WAL frames

Author: penberg

libsql-ffi/bundled/SQLite3MultipleCiphers/src/sqlite3.c

@@ -65324,10 +65324,17 @@ SQLITE_PRIVATE int sqlite3PagerWalBeginCommit(Pager *pPager) {
 }
 
 SQLITE_PRIVATE int sqlite3PagerWalEndCommit(Pager *pPager) {
+  int rc = SQLITE_ERROR;
   if (!pagerUseWal(pPager)) {
-    return SQLITE_ERROR;
+    return rc;
   }
-  return pPager->wal->methods.xEndWriteTransaction(pPager->wal->pData);
+  rc = pPager->wal->methods.xEndWriteTransaction(pPager->wal->pData);
+  if (rc != SQLITE_OK) {
+    return rc;
+  }
+  pager_reset(pPager);
+  pager_unlock(pPager);
+  return rc;
 }
 
 SQLITE_PRIVATE int sqlite3PagerWalInsert(Pager *pPager, unsigned int iFrame, void *pBuf, unsigned int nBuf) {

libsql-ffi/bundled/src/sqlite3.c

@@ -65324,10 +65324,17 @@ SQLITE_PRIVATE int sqlite3PagerWalBeginCommit(Pager *pPager) {
 }
 
 SQLITE_PRIVATE int sqlite3PagerWalEndCommit(Pager *pPager) {
+  int rc = SQLITE_ERROR;
   if (!pagerUseWal(pPager)) {
-    return SQLITE_ERROR;
+    return rc;
   }
-  return pPager->wal->methods.xEndWriteTransaction(pPager->wal->pData);
+  rc = pPager->wal->methods.xEndWriteTransaction(pPager->wal->pData);
+  if (rc != SQLITE_OK) {
+    return rc;
+  }
+  pager_reset(pPager);
+  pager_unlock(pPager);
+  return rc;
 }
 
 SQLITE_PRIVATE int sqlite3PagerWalInsert(Pager *pPager, unsigned int iFrame, void *pBuf, unsigned int nBuf) {

libsql-sqlite3/src/pager.c

@@ -7813,10 +7813,17 @@ int sqlite3PagerWalBeginCommit(Pager *pPager) {
 }
 
 int sqlite3PagerWalEndCommit(Pager *pPager) {
+  int rc = SQLITE_ERROR;
   if (!pagerUseWal(pPager)) {
-    return SQLITE_ERROR;
+    return rc;
   }
-  return pPager->wal->methods.xEndWriteTransaction(pPager->wal->pData);
+  rc = pPager->wal->methods.xEndWriteTransaction(pPager->wal->pData);
+  if (rc != SQLITE_OK) {
+    return rc;
+  }
+  pager_reset(pPager);
+  pager_unlock(pPager);
+  return rc;
 }
 
 int sqlite3PagerWalInsert(Pager *pPager, unsigned int iFrame, void *pBuf, unsigned int nBuf) {

libsql-sqlite3/src/test_walapi.c

@@ -119,12 +119,42 @@ void test_sync_by_parts() {
     cmp_data(db_primary, db_backup);
 }
 
+// This test case writes to a local database, syncs it to remote, and then verifies the remote.
+// The test then writes some more to local database, syncs it again, and verifies the remote again.
+void test_sync_while_reading() {
+     sqlite3 *db_primary, *db_backup;
+    unsigned int max_frame;
+    open_db("primary_test_sync_while_reading.db", &db_primary);
+    ensure(sqlite3_exec(db_primary, "CREATE TABLE t (x)", 0, 0, 0) == SQLITE_OK, "failed to insert data\n");
+    ensure(sqlite3_exec(db_primary, "INSERT INTO t VALUES (randomblob(4 * 1024))", 0, 0, 0) == SQLITE_OK, "failed to insert data\n");
+    ensure(sqlite3_exec(db_primary, "INSERT INTO t VALUES (randomblob(1 * 1024))", 0, 0, 0) == SQLITE_OK, "failed to insert data\n");
+    ensure(sqlite3_exec(db_primary, "INSERT INTO t VALUES (randomblob(1 * 1024))", 0, 0, 0) == SQLITE_OK, "failed to insert data\n");
+
+    open_db("backup_test_sync_while_reading.db", &db_backup);
+    ensure(libsql_wal_frame_count(db_backup, &max_frame) == SQLITE_OK, "failed to get frames count: %s\n", sqlite3_errmsg(db_backup));
+    assert(max_frame == 0);
+    
+    eprintf("start full sync\n");
+    sync_db(db_primary, db_backup);
+    cmp_data(db_primary, db_backup);
+
+    ensure(sqlite3_exec(db_primary, "INSERT INTO t VALUES (randomblob(4 * 1024))", 0, 0, 0) == SQLITE_OK, "failed to insert data\n");
+    ensure(sqlite3_exec(db_primary, "INSERT INTO t VALUES (randomblob(1 * 1024))", 0, 0, 0) == SQLITE_OK, "failed to insert data\n");
+    ensure(sqlite3_exec(db_primary, "INSERT INTO t VALUES (randomblob(1 * 1024))", 0, 0, 0) == SQLITE_OK, "failed to insert data\n");
+    sync_db(db_primary, db_backup);
+    cmp_data(db_primary, db_backup); 
+}
+
 int main(int argc, char *argv[])
 {
     test_huge_payload();
     printf("============= OK test_huge_payload\n");
 
     test_sync_by_parts();
     printf("============= OK test_sync_by_parts\n");
+
+    test_sync_while_reading();
+    printf("============= OK test_sync_while_reading\n");
+
     return 0;
 }