Implement a cancelation mechanism for queries.

Added new API to enable cancelation of SQLite and content provider
queries by means of a CancelationSignal object.  The application
creates a CancelationSignal object and passes it as an argument
to the query.  The cancelation signal can then be used to cancel
the query while it is executing.

If the cancelation signal is raised before the query is executed,
then it is immediately terminated.

Change-Id: If2c76e9a7e56ea5e98768b6d4f225f0a1ca61c61

2 files changed, 64 insertions, 31 deletions

diff --git a/core/jni/android_database_SQLiteCommon.cpp b/core/jni/android_database_SQLiteCommon.cpp
index a94b9d2..3484467 100644
--- a/core/jni/android_database_SQLiteCommon.cpp
+++ b/core/jni/android_database_SQLiteCommon.cpp
@@ -68,50 +68,53 @@ void throw_sqlite3_exception(JNIEnv* env, int errcode,
             exceptionClass = "android/database/sqlite/SQLiteDatabaseCorruptException";
             break;
         case SQLITE_CONSTRAINT:
-           exceptionClass = "android/database/sqlite/SQLiteConstraintException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteConstraintException";
+            break;
         case SQLITE_ABORT:
-           exceptionClass = "android/database/sqlite/SQLiteAbortException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteAbortException";
+            break;
         case SQLITE_DONE:
-           exceptionClass = "android/database/sqlite/SQLiteDoneException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteDoneException";
+            break;
         case SQLITE_FULL:
-           exceptionClass = "android/database/sqlite/SQLiteFullException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteFullException";
+            break;
         case SQLITE_MISUSE:
-           exceptionClass = "android/database/sqlite/SQLiteMisuseException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteMisuseException";
+            break;
         case SQLITE_PERM:
-           exceptionClass = "android/database/sqlite/SQLiteAccessPermException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteAccessPermException";
+            break;
         case SQLITE_BUSY:
-           exceptionClass = "android/database/sqlite/SQLiteDatabaseLockedException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteDatabaseLockedException";
+            break;
         case SQLITE_LOCKED:
-           exceptionClass = "android/database/sqlite/SQLiteTableLockedException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteTableLockedException";
+            break;
         case SQLITE_READONLY:
-           exceptionClass = "android/database/sqlite/SQLiteReadOnlyDatabaseException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteReadOnlyDatabaseException";
+            break;
         case SQLITE_CANTOPEN:
-           exceptionClass = "android/database/sqlite/SQLiteCantOpenDatabaseException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteCantOpenDatabaseException";
+            break;
         case SQLITE_TOOBIG:
-           exceptionClass = "android/database/sqlite/SQLiteBlobTooBigException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteBlobTooBigException";
+            break;
         case SQLITE_RANGE:
-           exceptionClass = "android/database/sqlite/SQLiteBindOrColumnIndexOutOfRangeException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteBindOrColumnIndexOutOfRangeException";
+            break;
         case SQLITE_NOMEM:
-           exceptionClass = "android/database/sqlite/SQLiteOutOfMemoryException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteOutOfMemoryException";
+            break;
         case SQLITE_MISMATCH:
-           exceptionClass = "android/database/sqlite/SQLiteDatatypeMismatchException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteDatatypeMismatchException";
+            break;
+        case SQLITE_INTERRUPT:
+            exceptionClass = "android/content/OperationCanceledException";
+            break;
         default:
-           exceptionClass = "android/database/sqlite/SQLiteException";
-           break;
+            exceptionClass = "android/database/sqlite/SQLiteException";
+            break;
     }
 
     if (sqlite3Message != NULL && message != NULL) {
diff --git a/core/jni/android_database_SQLiteConnection.cpp b/core/jni/android_database_SQLiteConnection.cpp
index d0d53f6..e061ac3 100644
--- a/core/jni/android_database_SQLiteConnection.cpp
+++ b/core/jni/android_database_SQLiteConnection.cpp
@@ -67,8 +67,10 @@ struct SQLiteConnection {
     const String8 path;
     const String8 label;
 
+    volatile bool canceled;
+
     SQLiteConnection(sqlite3* db, int openFlags, const String8& path, const String8& label) :
-        db(db), openFlags(openFlags), path(path), label(label) { }
+        db(db), openFlags(openFlags), path(path), label(label), canceled(false) { }
 };
 
 // Called each time a statement begins execution, when tracing is enabled.
@@ -85,6 +87,12 @@ static void sqliteProfileCallback(void *data, const char *sql, sqlite3_uint64 tm
             connection->label.string(), sql, tm * 0.000001f);
 }
 
+// Called after each SQLite VM instruction when cancelation is enabled.
+static int sqliteProgressHandlerCallback(void* data) {
+    SQLiteConnection* connection = static_cast<SQLiteConnection*>(data);
+    return connection->canceled;
+}
+
 
 static jint nativeOpen(JNIEnv* env, jclass clazz, jstring pathStr, jint openFlags,
         jstring labelStr, jboolean enableTrace, jboolean enableProfile) {
@@ -871,6 +879,24 @@ static jint nativeGetDbLookaside(JNIEnv* env, jobject clazz, jint connectionPtr)
     return cur;
 }
 
+static void nativeCancel(JNIEnv* env, jobject clazz, jint connectionPtr) {
+    SQLiteConnection* connection = reinterpret_cast<SQLiteConnection*>(connectionPtr);
+    connection->canceled = true;
+}
+
+static void nativeResetCancel(JNIEnv* env, jobject clazz, jint connectionPtr,
+        jboolean cancelable) {
+    SQLiteConnection* connection = reinterpret_cast<SQLiteConnection*>(connectionPtr);
+    connection->canceled = false;
+
+    if (cancelable) {
+        sqlite3_progress_handler(connection->db, 4, sqliteProgressHandlerCallback,
+                connection);
+    } else {
+        sqlite3_progress_handler(connection->db, 0, NULL, NULL);
+    }
+}
+
 
 static JNINativeMethod sMethods[] =
 {
@@ -923,6 +949,10 @@ static JNINativeMethod sMethods[] =
             (void*)nativeExecuteForCursorWindow },
     { "nativeGetDbLookaside", "(I)I",
             (void*)nativeGetDbLookaside },
+    { "nativeCancel", "(I)V",
+            (void*)nativeCancel },
+    { "nativeResetCancel", "(IZ)V",
+            (void*)nativeResetCancel },
 };
 
 #define FIND_CLASS(var, className) \