static jboolean setNumColumns(JNIEnv * env, jobject object, jint columnNum)
{
CursorWindow * window = GET_WINDOW(env, object);
return window->setNumColumns(columnNum);
}
static jboolean nativeSetNumColumns(JNIEnv* env, jclass clazz, jlong windowPtr,
jint columnNum) {
CursorWindow* window = reinterpret_cast<CursorWindow*>(windowPtr);
status_t status = window->setNumColumns(columnNum);
return status == OK;
}
static jlong nativeExecuteForCursorWindow(JNIEnv* env, jclass clazz,
jlong connectionPtr, jlong statementPtr, jlong windowPtr,
jint startPos, jint requiredPos, jboolean countAllRows) {
SQLiteConnection* connection = reinterpret_cast<SQLiteConnection*>(connectionPtr);
sqlite3_stmt* statement = reinterpret_cast<sqlite3_stmt*>(statementPtr);
CursorWindow* window = reinterpret_cast<CursorWindow*>(windowPtr);
status_t status = window->clear();
if (status) {
String8 msg;
msg.appendFormat("Failed to clear the cursor window, status=%d", status);
throw_sqlite3_exception(env, connection->db, msg.string());
return 0;
}
int numColumns = sqlite3_column_count(statement);
status = window->setNumColumns(numColumns);
if (status) {
String8 msg;
msg.appendFormat("Failed to set the cursor window column count to %d, status=%d",
numColumns, status);
throw_sqlite3_exception(env, connection->db, msg.string());
return 0;
}
int retryCount = 0;
int totalRows = 0;
int addedRows = 0;
bool windowFull = false;
bool gotException = false;
while (!gotException && (!windowFull || countAllRows)) {
int err = sqlite3_step(statement);
if (err == SQLITE_ROW) {
LOG_WINDOW("Stepped statement %p to row %d", statement, totalRows);
retryCount = 0;
totalRows += 1;
// Skip the row if the window is full or we haven't reached the start position yet.
if (startPos >= totalRows || windowFull) {
continue;
}
CopyRowResult cpr = copyRow(env, window, statement, numColumns, startPos, addedRows);
if (cpr == CPR_FULL && addedRows && startPos + addedRows <= requiredPos) {
// We filled the window before we got to the one row that we really wanted.
// Clear the window and start filling it again from here.
// TODO: Would be nicer if we could progressively replace earlier rows.
window->clear();
window->setNumColumns(numColumns);
startPos += addedRows;
addedRows = 0;
cpr = copyRow(env, window, statement, numColumns, startPos, addedRows);
}
if (cpr == CPR_OK) {
addedRows += 1;
} else if (cpr == CPR_FULL) {
windowFull = true;
} else {
gotException = true;
}
} else if (err == SQLITE_DONE) {
// All rows processed, bail
LOG_WINDOW("Processed all rows");
break;
} else if (err == SQLITE_LOCKED || err == SQLITE_BUSY) {
// The table is locked, retry
LOG_WINDOW("Database locked, retrying");
if (retryCount > 50) {
ALOGE("Bailing on database busy retry");
throw_sqlite3_exception(env, connection->db, "retrycount exceeded");
gotException = true;
} else {
// Sleep to give the thread holding the lock a chance to finish
usleep(1000);
retryCount++;
}
} else {
throw_sqlite3_exception(env, connection->db);
gotException = true;
}
}
LOG_WINDOW("Resetting statement %p after fetching %d rows and adding %d rows"
"to the window in %d bytes",
statement, totalRows, addedRows, window->size() - window->freeSpace());
sqlite3_reset(statement);
// Report the total number of rows on request.
if (startPos > totalRows) {
ALOGE("startPos %d > actual rows %d", startPos, totalRows);
}
jlong result = jlong(startPos) << 32 | jlong(totalRows);
return result;
}