diff options
Diffstat (limited to 'en/devices/architecture')
| -rw-r--r-- | en/devices/architecture/hidl-java/index.html | 12 | ||||
| -rw-r--r-- | en/devices/architecture/hidl/services.html | 4 | ||||
| -rw-r--r-- | en/devices/architecture/hidl/threading.html | 24 |
3 files changed, 28 insertions, 12 deletions
diff --git a/en/devices/architecture/hidl-java/index.html b/en/devices/architecture/hidl-java/index.html index c4218160..45eefc7d 100644 --- a/en/devices/architecture/hidl-java/index.html +++ b/en/devices/architecture/hidl-java/index.html @@ -68,8 +68,9 @@ The static version of the library is also available as <pre class="prettyprint"> import android.hardware.foo.V1_0.IFoo; ... -IFoo server = IFoo.getService(); // throws exception if not available -IFoo anotherServer = IFoo.getService("second_impl"); +// retry to wait until the service starts up if it is in the manifest +IFoo server = IFoo.getService(true /* retry */); // throws NoSuchElementException if not available +IFoo anotherServer = IFoo.getService("second_impl", true /* retry */); server.doSomething(…); </pre> </li> @@ -82,6 +83,9 @@ callbacks from HALs.</p> <p class=warning><strong>Warning</strong>: Do not implement a driver (HAL) in Java. We strongly recommend you implement drivers in C++.</p> +<p class=warning><strong>Warning</strong>: Java drivers must be in a separate +process from their clients (same process communication is not supported).</p> + <p>For interface <code>IFooCallback</code> in version 1.0 of package <code>android.hardware.foo</code>, you can implement your interface in Java using the following steps:</p> @@ -142,7 +146,7 @@ class FooCallback extends IFooCallback.Stub { .... // Get the service you will be receiving callbacks from. // This also starts the threadpool for your callback service. -IFoo server = IFoo.getService(); // throws exception if not available +IFoo server = IFoo.getService(true /* retry */); // throws NoSuchElementException if not available .... // This must be a persistent instance variable, not local, // to avoid premature garbage collection. @@ -173,7 +177,7 @@ interface IBetterFoo extends IFoo { extended interface:</p> <pre class="prettyprint"> -IFoo baseService = Foo.getService(); +IFoo baseService = IFoo.getService(true /* retry */); // throws NoSuchElementException if not available IBetterFoo extendedService = IBetterFoo.castFrom(baseService); if (extendedService != null) { // The service implements the extended interface. diff --git a/en/devices/architecture/hidl/services.html b/en/devices/architecture/hidl/services.html index 805bc800..1d2deccb 100644 --- a/en/devices/architecture/hidl/services.html +++ b/en/devices/architecture/hidl/services.html @@ -53,10 +53,10 @@ version, calling <code>getService</code> on the desired HAL class:</p> <pre class="prettyprint"> // C++ sp<V1_1::IFooService> service = V1_1::IFooService::getService(); -sp<V1_1::IFooService> alternateService = 1_1::IFooService::getService("another_foo_service"); +sp<V1_1::IFooService> alternateService = V1_1::IFooService::getService("another_foo_service"); // Java V1_1.IFooService; service = V1_1.IFooService.getService(true /* retry */); -V1_1.IFooService; alternateService = 1_1.IFooService.getService("another", true /* retry */); +V1_1.IFooService; alternateService = V1_1.IFooService.getService("another", true /* retry */); </pre> <p>Each version of a HIDL interface is treated as a separate interface. Thus, diff --git a/en/devices/architecture/hidl/threading.html b/en/devices/architecture/hidl/threading.html index 5b8fa038..26c2cc12 100644 --- a/en/devices/architecture/hidl/threading.html +++ b/en/devices/architecture/hidl/threading.html @@ -48,11 +48,11 @@ available, it blocks until one is available.</p> <p>If the server has only one thread, then calls into the server are completed in order. A server with more than one thread may complete calls out of order -even if the client has only one thread. As <code>oneway</code> calls do not -block the client, multiple <code>oneway</code> calls may be processed -simultaneously or out of order by a server with more than one thread, and -<code>oneway</code> calls may be processed concurrently with a subsequent -blocking call.</p> +even if the client has only one thread. However, for a given interface object, +<code>oneway</code> calls are guaranteed to be ordered (see +<a href="#model">Server threading model</a>). For a multi-threaded server that +hosts multiple interfaces, <code>oneway</code> calls to different interfaces +may be processed concurrently with each other or other blocking calls.</p> <p>Multiple nested calls will be sent on the same hwbinder thread. For instance, if a process (A) makes a synchronous call from a hwbinder thread into process (B), @@ -160,7 +160,19 @@ server returns a <code>Return<void></code> object.</p> <h3 id=oneway>Oneway calls</h3> <p>When a function is marked <code>oneway</code>, the client returns immediately -and does not wait for the server to complete its function call invocation.</p> +and does not wait for the server to complete its function call invocation. At the +surface (and in aggregate), this means the function call takes half the +time because it is executing half the code, but when writing implementations that +are performance sensitive, this has some scheduling implications. Normally, +using a oneway call causes the callee to continue to be scheduled whereas +using a normal synchronous call causes the scheduler to immediately transfer +from the callee to the caller process. This is a performance optimization in +binder. For services where the oneway call must be executed in the target process +with a high priority, the scheduling policy of the receiving service can be +changed. In C++, using <code>libhidltransport</code>'s method +<code>setMinSchedulerPolicy</code> with the scheduler priorities and policies +defined in <code>sched.h</code> ensures that all calls into the service run at +least at the set scheduling policy and priority.</p> </body> </html> |