CronetEngine

public static final int ACTIVE_REQUEST_COUNT_UNKNOWN = -1

The value of the active request count is unknown

public static final int CONNECTION_METRIC_UNKNOWN = -1

The value of a connection metric is unknown.

public static final int EFFECTIVE_CONNECTION_TYPE_2G = 3

The estimate of the effective connection type is 2G.

public static final int EFFECTIVE_CONNECTION_TYPE_3G = 4

The estimate of the effective connection type is 3G.

public static final int EFFECTIVE_CONNECTION_TYPE_4G = 5

The estimate of the effective connection type is 4G.

public static final int EFFECTIVE_CONNECTION_TYPE_OFFLINE = 1

The device is offline.

public static final int EFFECTIVE_CONNECTION_TYPE_SLOW_2G = 2

The estimate of the effective connection type is slow 2G.

public static final int EFFECTIVE_CONNECTION_TYPE_UNKNOWN = 0

The estimate of the effective connection type is unknown.

public static final long UNBIND_NETWORK_HANDLE = -1

The value to be used to undo any previous network binding.

public void addRequestFinishedListener(RequestFinishedInfo.Listener listener)

Registers a listener that gets called after the end of each request with the request info.

The listener is called on an java.util.concurrent.Executor provided by the listener.

public void addRttListener(NetworkQualityRttListener listener)

Registers a listener that gets called whenever the network quality estimator witnesses a sample round trip time. This must be called after enableNetworkQualityEstimator, and with throw an exception otherwise. Round trip times may be recorded at various layers of the network stack, including TCP, QUIC, and at the URL request layer. The listener is called on the java.util.concurrent.Executor that is passed to enableNetworkQualityEstimator.

public void addThroughputListener(NetworkQualityThroughputListener listener)

Registers a listener that gets called whenever the network quality estimator witnesses a sample throughput measurement. This must be called after enableNetworkQualityEstimator. Throughput observations are computed by measuring bytes read over the active network interface at times when at least one URL response is being received. The listener is called on the java.util.concurrent.Executor that is passed to enableNetworkQualityEstimator.

public void bindToNetwork(long networkHandle)

Binds the engine to the specified network handle. All requests created through this engine will use the network associated to this handle. If this network disconnects all requests will fail, the exact error will depend on the stage of request processing when the network disconnects. Network handles can be obtained through Network#getNetworkHandle. Only available starting from Android Marshmallow.

public void configureNetworkQualityEstimatorForTesting(
    boolean useLocalHostRequests,
    boolean useSmallerResponses,
    boolean disableOfflineCheck
)

Configures the network quality estimator for testing. This must be called before round trip time and throughput listeners are added, and after the network quality estimator has been enabled.

public abstract URLStreamHandlerFactory createURLStreamHandlerFactory()

Creates a URLStreamHandlerFactory to handle HTTP and HTTPS traffic. An instance of this class can be installed via setURLStreamHandlerFactory thus using this CronetEngine by default for all requests created via openConnection.

Cronet does not use certain HTTP features provided via the system:

• the HTTP cache installed via HttpResponseCache.install()
• the HTTP authentication method installed via setDefault
• the HTTP cookie storage installed via setDefault

While Cronet supports and encourages requests using the HTTPS protocol, Cronet does not provide support for the HttpsURLConnection API. This lack of support also includes not using certain HTTPS features provided via the system:

• the HTTPS hostname verifier installed via HttpsURLConnection.setDefaultHostnameVerifier()
• the HTTPS socket factory installed via HttpsURLConnection.setDefaultSSLSocketFactory()

public int getActiveRequestCount()

Returns the number of active requests.

A request becomes "active" in UrlRequest.start(), assuming that method does not throw an exception. It becomes inactive when all callbacks have returned and no additional callbacks can be triggered in the future. In practice, that means the request is inactive once onSucceeded/onCanceled/onFailed has returned and all request finished listeners have returned. Cronet requests's lifecycle for more information.

public int getDownstreamThroughputKbps()

Returns the downstream throughput estimate (in kilobits per second) computed by the network quality estimator. Set to CONNECTION_METRIC_UNKNOWN if the value is unavailable. This must be called after enableNetworkQualityEstimator, and will throw an exception otherwise.

public int getEffectiveConnectionType()

Returns an estimate of the effective connection type computed by the network quality estimator. Call enableNetworkQualityEstimator to begin computing this value.

public int getHttpRttMs()

Returns the HTTP RTT estimate (in milliseconds) computed by the network quality estimator. Set to CONNECTION_METRIC_UNKNOWN if the value is unavailable. This must be called after enableNetworkQualityEstimator, and will throw an exception otherwise.

public int getTransportRttMs()

Returns the transport RTT estimate (in milliseconds) computed by the network quality estimator. Set to CONNECTION_METRIC_UNKNOWN if the value is unavailable. This must be called after enableNetworkQualityEstimator, and will throw an exception otherwise.

public abstract UrlRequest.Builder newUrlRequestBuilder(
    String url,
    UrlRequest.Callback callback,
    Executor executor
)

Creates a builder for UrlRequest. All callbacks for generated UrlRequest objects will be invoked on executor's threads. executor must not run tasks on the thread calling execute to prevent blocking networking operations and causing exceptions during shutdown.

public abstract URLConnection openConnection(URL url)

Establishes a new connection to the resource specified by the URLurl.

Note: Cronet's java.net.HttpURLConnection implementation is subject to certain limitations, see createURLStreamHandlerFactory for details.

public void removeRequestFinishedListener(RequestFinishedInfo.Listener listener)

Removes a finished request listener.

public void removeRttListener(NetworkQualityRttListener listener)

Removes a listener of round trip times if previously registered with addRttListener. This should be called after a NetworkQualityRttListener is added in order to stop receiving observations.

public void removeThroughputListener(NetworkQualityThroughputListener listener)

Removes a listener of throughput. This should be called after a NetworkQualityThroughputListener is added with addThroughputListener in order to stop receiving observations.

public abstract void shutdown()

Shuts down the CronetEngine if there are no active requests, otherwise throws an exception.

Cannot be called on network thread - the thread Cronet calls into Executor on (which is different from the thread the Executor invokes callbacks on). May block until all the CronetEngine's resources have been cleaned up.

public void startNetLogToDisk(String dirPath, boolean logAll, int maxSize)

Starts NetLog logging to a specified directory with a bounded size. The NetLog will contain events emitted by all live CronetEngines. The NetLog is useful for debugging. Once logging has stopped stopNetLog, the data will be written to netlog.json in dirPath. If logging is interrupted, you can stitch the files found in .inprogress subdirectory manually using: https://chromium.googlesource.com/chromium/src/+/main/net/tools/stitch_net_log_files.py. The log can be viewed using a Chrome browser navigated to chrome://net-internals/#import.

public abstract void startNetLogToFile(String fileName, boolean logAll)

Starts NetLog logging to a file. The NetLog will contain events emitted by all live CronetEngines. The NetLog is useful for debugging. The file can be viewed using a Chrome browser navigated to chrome://net-internals/#import

public abstract void stopNetLog()

Stops NetLog logging and flushes file to disk. If a logging session is not in progress, this call is ignored.