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Merge "Improve documentation for NetworkCallbacks." am: c1ea43fa1c

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am: 3747ac3067

Change-Id: If8478eea266decd897382fe1e6efffa23f77f7ab
This commit is contained in:
Chalard Jean
2019-10-09 23:21:02 -07:00
committed by android-build-merger
parent 22ba70df25 3747ac3067
commit 30baa870e5
1 changed files with 156 additions and 83 deletions
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239
core/java/android/net/ConnectivityManager.java
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@@ -3265,42 +3265,77 @@ public class ConnectivityManager {
/**
* Called when the framework connects and has declared a new network ready for use.
* This callback may be called more than once if the {@link Network} that is
* satisfying the request changes. This will always immediately be followed by a
* call to {@link #onCapabilitiesChanged(Network, NetworkCapabilities)} then by a
* call to {@link #onLinkPropertiesChanged(Network, LinkProperties)}, and a call to
* {@link #onBlockedStatusChanged(Network, boolean)}.
*
* <p>For callbacks registered with {@link #registerNetworkCallback}, multiple networks may
* be available at the same time, and onAvailable will be called for each of these as they
* appear.
*
* <p>For callbacks registered with {@link #requestNetwork} and
* {@link #registerDefaultNetworkCallback}, this means the network passed as an argument
* is the new best network for this request and is now tracked by this callback ; this
* callback will no longer receive method calls about other networks that may have been
* passed to this method previously. The previously-best network may have disconnected, or
* it may still be around and the newly-best network may simply be better.
*
* <p>Starting with {@link android.os.Build.VERSION_CODES#O}, this will always immediately
* be followed by a call to {@link #onCapabilitiesChanged(Network, NetworkCapabilities)}
* then by a call to {@link #onLinkPropertiesChanged(Network, LinkProperties)}, and a call
* to {@link #onBlockedStatusChanged(Network, boolean)}.
*
* <p>Do NOT call {@link #getNetworkCapabilities(Network)} or
* {@link #getLinkProperties(Network)} or other synchronous ConnectivityManager methods in
* this callback as this is prone to race conditions (there is no guarantee the objects
* returned by these methods will be current). Instead, wait for a call to
* {@link #onCapabilitiesChanged(Network, NetworkCapabilities)} and
* {@link #onLinkPropertiesChanged(Network, LinkProperties)} whose arguments are guaranteed
* to be well-ordered with respect to other callbacks.
*
* @param network The {@link Network} of the satisfying network.
*/
public void onAvailable(@NonNull Network network) {}
/**
* Called when the network is about to be disconnected. Often paired with an
* {@link NetworkCallback#onAvailable} call with the new replacement network
* for graceful handover. This may not be called if we have a hard loss
* (loss without warning). This may be followed by either a
* {@link NetworkCallback#onLost} call or a
* {@link NetworkCallback#onAvailable} call for this network depending
* on whether we lose or regain it.
* Called when the network is about to be lost, typically because there are no outstanding
* requests left for it. This may be paired with a {@link NetworkCallback#onAvailable} call
* with the new replacement network for graceful handover. This method is not guaranteed
* to be called before {@link NetworkCallback#onLost} is called, for example in case a
* network is suddenly disconnected.
*
* @param network The {@link Network} that is about to be disconnected.
* @param maxMsToLive The time in ms the framework will attempt to keep the
* network connected. Note that the network may suffer a
* hard loss at any time.
* <p>Do NOT call {@link #getNetworkCapabilities(Network)} or
* {@link #getLinkProperties(Network)} or other synchronous ConnectivityManager methods in
* this callback as this is prone to race conditions ; calling these methods while in a
* callback may return an outdated or even a null object.
*
* @param network The {@link Network} that is about to be lost.
* @param maxMsToLive The time in milliseconds the system intends to keep the network
* connected for graceful handover; note that the network may still
* suffer a hard loss at any time.
*/
public void onLosing(@NonNull Network network, int maxMsToLive) {}
/**
* Called when the framework has a hard loss of the network or when the
* graceful failure ends.
* Called when a network disconnects or otherwise no longer satisfies this request or
* callback.
*
* <p>If the callback was registered with requestNetwork() or
* registerDefaultNetworkCallback(), it will only be invoked against the last network
* returned by onAvailable() when that network is lost and no other network satisfies
* the criteria of the request.
*
* <p>If the callback was registered with registerNetworkCallback() it will be called for
* each network which no longer satisfies the criteria of the callback.
*
* <p>Do NOT call {@link #getNetworkCapabilities(Network)} or
* {@link #getLinkProperties(Network)} or other synchronous ConnectivityManager methods in
* this callback as this is prone to race conditions ; calling these methods while in a
* callback may return an outdated or even a null object.
*
* @param network The {@link Network} lost.
*/
public void onLost(@NonNull Network network) {}
/**
* Called if no network is found in the timeout time specified in
* Called if no network is found within the timeout time specified in
* {@link #requestNetwork(NetworkRequest, NetworkCallback, int)} call or if the
* requested network request cannot be fulfilled (whether or not a timeout was
* specified). When this callback is invoked the associated
@@ -3310,8 +3345,15 @@ public class ConnectivityManager {
public void onUnavailable() {}
/**
* Called when the network the framework connected to for this request
* changes capabilities but still satisfies the stated need.
* Called when the network corresponding to this request changes capabilities but still
* satisfies the requested criteria.
*
* <p>Starting with {@link android.os.Build.VERSION_CODES#O} this method is guaranteed
* to be called immediately after {@link #onAvailable}.
*
* <p>Do NOT call {@link #getLinkProperties(Network)} or other synchronous
* ConnectivityManager methods in this callback as this is prone to race conditions :
* calling these methods while in a callback may return an outdated or even a null object.
*
* @param network The {@link Network} whose capabilities have changed.
* @param networkCapabilities The new {@link android.net.NetworkCapabilities} for this
@@ -3321,8 +3363,14 @@ public class ConnectivityManager {
@NonNull NetworkCapabilities networkCapabilities) {}
/**
* Called when the network the framework connected to for this request
* changes {@link LinkProperties}.
* Called when the network corresponding to this request changes {@link LinkProperties}.
*
* <p>Starting with {@link android.os.Build.VERSION_CODES#O} this method is guaranteed
* to be called immediately after {@link #onAvailable}.
*
* <p>Do NOT call {@link #getNetworkCapabilities(Network)} or other synchronous
* ConnectivityManager methods in this callback as this is prone to race conditions :
* calling these methods while in a callback may return an outdated or even a null object.
*
* @param network The {@link Network} whose link properties have changed.
* @param linkProperties The new {@link LinkProperties} for this network.
@@ -3331,12 +3379,20 @@ public class ConnectivityManager {
@NonNull LinkProperties linkProperties) {}
/**
* Called when the network the framework connected to for this request
* goes into {@link NetworkInfo.State#SUSPENDED}.
* This generally means that while the TCP connections are still live,
* temporarily network data fails to transfer. Specifically this is used
* on cellular networks to mask temporary outages when driving through
* a tunnel, etc.
* Called when the network the framework connected to for this request suspends data
* transmission temporarily.
*
* <p>This generally means that while the TCP connections are still live temporarily
* network data fails to transfer. To give a specific example, this is used on cellular
* networks to mask temporary outages when driving through a tunnel, etc. In general this
* means read operations on sockets on this network will block once the buffers are
* drained, and write operations will block once the buffers are full.
*
* <p>Do NOT call {@link #getNetworkCapabilities(Network)} or
* {@link #getLinkProperties(Network)} or other synchronous ConnectivityManager methods in
* this callback as this is prone to race conditions (there is no guarantee the objects
* returned by these methods will be current).
*
* @hide
*/
public void onNetworkSuspended(@NonNull Network network) {}
@@ -3345,6 +3401,12 @@ public class ConnectivityManager {
* Called when the network the framework connected to for this request
* returns from a {@link NetworkInfo.State#SUSPENDED} state. This should always be
* preceded by a matching {@link NetworkCallback#onNetworkSuspended} call.
* <p>Do NOT call {@link #getNetworkCapabilities(Network)} or
* {@link #getLinkProperties(Network)} or other synchronous ConnectivityManager methods in
* this callback as this is prone to race conditions : calling these methods while in a
* callback may return an outdated or even a null object.
*
* @hide
*/
public void onNetworkResumed(@NonNull Network network) {}
@@ -3352,6 +3414,11 @@ public class ConnectivityManager {
/**
* Called when access to the specified network is blocked or unblocked.
*
* <p>Do NOT call {@link #getNetworkCapabilities(Network)} or
* {@link #getLinkProperties(Network)} or other synchronous ConnectivityManager methods in
* this callback as this is prone to race conditions : calling these methods while in a
* callback may return an outdated or even a null object.
*
* @param network The {@link Network} whose blocked status has changed.
* @param blocked The blocked status of this {@link Network}.
*/
@@ -3588,13 +3655,51 @@ public class ConnectivityManager {
/**
* Request a network to satisfy a set of {@link android.net.NetworkCapabilities}.
*
* This {@link NetworkRequest} will live until released via
* {@link #unregisterNetworkCallback(NetworkCallback)} or the calling application exits. A
* version of the method which takes a timeout is
* {@link #requestNetwork(NetworkRequest, NetworkCallback, int)}.
* Status of the request can be followed by listening to the various
* callbacks described in {@link NetworkCallback}. The {@link Network}
* can be used to direct traffic to the network.
* <p>This method will attempt to find the best network that matches the passed
* {@link NetworkRequest}, and to bring up one that does if none currently satisfies the
* criteria. The platform will evaluate which network is the best at its own discretion.
* Throughput, latency, cost per byte, policy, user preference and other considerations
* may be factored in the decision of what is considered the best network.
*
* <p>As long as this request is outstanding, the platform will try to maintain the best network
* matching this request, while always attempting to match the request to a better network if
* possible. If a better match is found, the platform will switch this request to the now-best
* network and inform the app of the newly best network by invoking
* {@link NetworkCallback#onAvailable(Network)} on the provided callback. Note that the platform
* will not try to maintain any other network than the best one currently matching the request:
* a network not matching any network request may be disconnected at any time.
*
* <p>For example, an application could use this method to obtain a connected cellular network
* even if the device currently has a data connection over Ethernet. This may cause the cellular
* radio to consume additional power. Or, an application could inform the system that it wants
* a network supporting sending MMSes and have the system let it know about the currently best
* MMS-supporting network through the provided {@link NetworkCallback}.
*
* <p>The status of the request can be followed by listening to the various callbacks described
* in {@link NetworkCallback}. The {@link Network} object passed to the callback methods can be
* used to direct traffic to the network (although accessing some networks may be subject to
* holding specific permissions). Callers will learn about the specific characteristics of the
* network through
* {@link NetworkCallback#onCapabilitiesChanged(Network, NetworkCapabilities)} and
* {@link NetworkCallback#onLinkPropertiesChanged(Network, LinkProperties)}. The methods of the
* provided {@link NetworkCallback} will only be invoked due to changes in the best network
* matching the request at any given time; therefore when a better network matching the request
* becomes available, the {@link NetworkCallback#onAvailable(Network)} method is called
* with the new network after which no further updates are given about the previously-best
* network, unless it becomes the best again at some later time. All callbacks are invoked
* in order on the same thread, which by default is a thread created by the framework running
* in the app.
* {@see #requestNetwork(NetworkRequest, NetworkCallback, Handler)} to change where the
* callbacks are invoked.
*
* <p>This{@link NetworkRequest} will live until released via
* {@link #unregisterNetworkCallback(NetworkCallback)} or the calling application exits, at
* which point the system may let go of the network at any time.
*
* <p>A version of this method which takes a timeout is
* {@link #requestNetwork(NetworkRequest, NetworkCallback, int)}, that an app can use to only
* wait for a limited amount of time for the network to become unavailable.
*
* <p>It is presently unsupported to request a network with mutable
* {@link NetworkCapabilities} such as
* {@link NetworkCapabilities#NET_CAPABILITY_VALIDATED} or
@@ -3602,7 +3707,7 @@ public class ConnectivityManager {
* as these {@code NetworkCapabilities} represent states that a particular
* network may never attain, and whether a network will attain these states
* is unknown prior to bringing up the network so the framework does not
* know how to go about satisfing a request with these capabilities.
* know how to go about satisfying a request with these capabilities.
*
* <p>This method requires the caller to hold either the
* {@link android.Manifest.permission#CHANGE_NETWORK_STATE} permission
@@ -3625,34 +3730,17 @@ public class ConnectivityManager {
/**
* Request a network to satisfy a set of {@link android.net.NetworkCapabilities}.
*
* This {@link NetworkRequest} will live until released via
* {@link #unregisterNetworkCallback(NetworkCallback)} or the calling application exits. A
* version of the method which takes a timeout is
* {@link #requestNetwork(NetworkRequest, NetworkCallback, int)}.
* Status of the request can be followed by listening to the various
* callbacks described in {@link NetworkCallback}. The {@link Network}
* can be used to direct traffic to the network.
* <p>It is presently unsupported to request a network with mutable
* {@link NetworkCapabilities} such as
* {@link NetworkCapabilities#NET_CAPABILITY_VALIDATED} or
* {@link NetworkCapabilities#NET_CAPABILITY_CAPTIVE_PORTAL}
* as these {@code NetworkCapabilities} represent states that a particular
* network may never attain, and whether a network will attain these states
* is unknown prior to bringing up the network so the framework does not
* know how to go about satisfying a request with these capabilities.
* This method behaves identically to {@link #requestNetwork(NetworkRequest, NetworkCallback)}
* but runs all the callbacks on the passed Handler.
*
* <p>This method requires the caller to hold either the
* {@link android.Manifest.permission#CHANGE_NETWORK_STATE} permission
* or the ability to modify system settings as determined by
* {@link android.provider.Settings.System#canWrite}.</p>
* <p>This method has the same permission requirements as
* {@link #requestNetwork(NetworkRequest, NetworkCallback)} and throws the same exceptions in
* the same conditions.
*
* @param request {@link NetworkRequest} describing this request.
* @param networkCallback The {@link NetworkCallback} to be utilized for this request. Note
* the callback must not be shared - it uniquely specifies this request.
* @param handler {@link Handler} to specify the thread upon which the callback will be invoked.
* @throws IllegalArgumentException if {@code request} contains invalid network capabilities.
* @throws SecurityException if missing the appropriate permissions.
* @throws RuntimeException if request limit per UID is exceeded.
*/
public void requestNetwork(@NonNull NetworkRequest request,
@NonNull NetworkCallback networkCallback, @NonNull Handler handler) {
@@ -3677,10 +3765,9 @@ public class ConnectivityManager {
* timeout) - {@link #registerNetworkCallback(NetworkRequest, NetworkCallback)} is provided
* for that purpose. Calling this method will attempt to bring up the requested network.
*
* <p>This method requires the caller to hold either the
* {@link android.Manifest.permission#CHANGE_NETWORK_STATE} permission
* or the ability to modify system settings as determined by
* {@link android.provider.Settings.System#canWrite}.</p>
* <p>This method has the same permission requirements as
* {@link #requestNetwork(NetworkRequest, NetworkCallback)} and throws the same exceptions in
* the same conditions.
*
* @param request {@link NetworkRequest} describing this request.
* @param networkCallback The {@link NetworkCallback} to be utilized for this request. Note
@@ -3688,9 +3775,6 @@ public class ConnectivityManager {
* @param timeoutMs The time in milliseconds to attempt looking for a suitable network
* before {@link NetworkCallback#onUnavailable()} is called. The timeout must
* be a positive value (i.e. >0).
* @throws IllegalArgumentException if {@code request} contains invalid network capabilities.
* @throws SecurityException if missing the appropriate permissions.
* @throws RuntimeException if request limit per UID is exceeded.
*/
public void requestNetwork(@NonNull NetworkRequest request,
@NonNull NetworkCallback networkCallback, int timeoutMs) {
@@ -3703,21 +3787,13 @@ public class ConnectivityManager {
* Request a network to satisfy a set of {@link android.net.NetworkCapabilities}, limited
* by a timeout.
*
* This function behaves identically to the version without timeout, but if a suitable
* network is not found within the given time (in milliseconds) the
* {@link NetworkCallback#onUnavailable} callback is called. The request can still be
* released normally by calling {@link #unregisterNetworkCallback(NetworkCallback)} but does
* not have to be released if timed-out (it is automatically released). Unregistering a
* request that timed out is not an error.
* This method behaves identically to
* {@link #requestNetwork(NetworkRequest, NetworkCallback, int)} but runs all the callbacks
* on the passed Handler.
*
* <p>Do not use this method to poll for the existence of specific networks (e.g. with a small
* timeout) - {@link #registerNetworkCallback(NetworkRequest, NetworkCallback)} is provided
* for that purpose. Calling this method will attempt to bring up the requested network.
*
* <p>This method requires the caller to hold either the
* {@link android.Manifest.permission#CHANGE_NETWORK_STATE} permission
* or the ability to modify system settings as determined by
* {@link android.provider.Settings.System#canWrite}.</p>
* <p>This method has the same permission requirements as
* {@link #requestNetwork(NetworkRequest, NetworkCallback, int)} and throws the same exceptions
* in the same conditions.
*
* @param request {@link NetworkRequest} describing this request.
* @param networkCallback The {@link NetworkCallback} to be utilized for this request. Note
@@ -3725,9 +3801,6 @@ public class ConnectivityManager {
* @param handler {@link Handler} to specify the thread upon which the callback will be invoked.
* @param timeoutMs The time in milliseconds to attempt looking for a suitable network
* before {@link NetworkCallback#onUnavailable} is called.
* @throws IllegalArgumentException if {@code request} contains invalid network capabilities.
* @throws SecurityException if missing the appropriate permissions.
* @throws RuntimeException if request limit per UID is exceeded.
*/
public void requestNetwork(@NonNull NetworkRequest request,
@NonNull NetworkCallback networkCallback, @NonNull Handler handler, int timeoutMs) {