gecko/mobile/android/base/sync/JSONRecordFetcher.java

133 lines
3.7 KiB
Java

package org.mozilla.gecko.sync;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import org.mozilla.gecko.sync.delegates.JSONRecordFetchDelegate;
import org.mozilla.gecko.sync.net.SyncStorageRecordRequest;
import org.mozilla.gecko.sync.net.SyncStorageRequestDelegate;
import org.mozilla.gecko.sync.net.SyncStorageResponse;
/**
* An object which fetches a chunk of JSON from a URI, using certain credentials,
* and informs its delegate of the result.
*/
public class JSONRecordFetcher {
private static final long DEFAULT_AWAIT_TIMEOUT_MSEC = 2 * 60 * 1000; // Two minutes.
private static final String LOG_TAG = "JSONRecordFetcher";
protected final String credentials;
protected final String uri;
protected JSONRecordFetchDelegate delegate;
public JSONRecordFetcher(final String uri, final String credentials) {
this.uri = uri;
this.credentials = credentials;
}
protected String getURI() {
return this.uri;
}
private class JSONFetchHandler implements SyncStorageRequestDelegate {
// SyncStorageRequestDelegate methods for fetching.
public String credentials() {
return credentials;
}
public String ifUnmodifiedSince() {
return null;
}
public void handleRequestSuccess(SyncStorageResponse response) {
if (response.wasSuccessful()) {
try {
delegate.handleSuccess(response.jsonObjectBody());
} catch (Exception e) {
handleRequestError(e);
}
return;
}
handleRequestFailure(response);
}
@Override
public void handleRequestFailure(SyncStorageResponse response) {
delegate.handleFailure(response);
}
@Override
public void handleRequestError(Exception ex) {
delegate.handleError(ex);
}
}
public void fetch(final JSONRecordFetchDelegate delegate) {
this.delegate = delegate;
try {
final SyncStorageRecordRequest r = new SyncStorageRecordRequest(this.getURI());
r.delegate = new JSONFetchHandler();
r.get();
} catch (Exception e) {
delegate.handleError(e);
}
}
private class LatchedJSONRecordFetchDelegate implements JSONRecordFetchDelegate {
public ExtendedJSONObject body = null;
public Exception exception = null;
private CountDownLatch latch;
public LatchedJSONRecordFetchDelegate(CountDownLatch latch) {
this.latch = latch;
}
@Override
public void handleFailure(SyncStorageResponse response) {
this.exception = new HTTPFailureException(response);
latch.countDown();
}
@Override
public void handleError(Exception e) {
this.exception = e;
latch.countDown();
}
@Override
public void handleSuccess(ExtendedJSONObject body) {
this.body = body;
latch.countDown();
}
}
/**
* Fetch the info record, blocking until it returns.
* @return the info record.
*/
public ExtendedJSONObject fetchBlocking() throws HTTPFailureException, Exception {
CountDownLatch latch = new CountDownLatch(1);
LatchedJSONRecordFetchDelegate delegate = new LatchedJSONRecordFetchDelegate(latch);
this.delegate = delegate;
this.fetch(delegate);
// Sanity wait: the resource itself will time out and throw after two
// minutes, so we just want to avoid coding errors causing us to block
// endlessly.
if (!latch.await(DEFAULT_AWAIT_TIMEOUT_MSEC, TimeUnit.MILLISECONDS)) {
Logger.warn(LOG_TAG, "Interrupted fetching info record.");
throw new InterruptedException("info fetch timed out.");
}
if (delegate.body != null) {
return delegate.body;
}
if (delegate.exception != null) {
throw delegate.exception;
}
throw new Exception("Unknown error.");
}
}