[discussion] What would improve Android integration experience

[yschimke]

I looked at modelling Android networks with proxies for each network, and potentially multiple concurrent paths to try to connect e.g. given three networks

N1 - Cellular (radio on/off), Provider DNS
N2 - Wifi (on, corp network with proxy), Corp DNS
N3 - VPN

And IPv4 and IPv6 addressable

Potentially the optimum route is connecting to all 6 combinations at once and seeing which one allowed a connection.

But also apps may have additional knowledge, e.g. some networks should be preferred for certain corp hosts, some large downloads should only be over wifi etc, some requests should maybe be failed once the network goes away, others retried.

Also some requests can be eagerly terminated once the platform takes away the network, even if a socket event is not received.

Also DNS/Proxy Changes should possibly cause connections to be dropped and apps to retry?

[yschimke]

Definitely not a 3.X change, but could be high value for a lot of apps if we solve the sort of problems that large internal teams in tech companies are already optimising around.

[swankjesse]

Very powerful stuff. Could go into our route selection.

[yschimke]

Probably best to tie in with #4530

[yschimke]

Another one: Exception translation

e.g. in Airplane mode, we could throw an AirplaneModeException?

java.net.UnknownHostException: Unable to resolve host "squareup.com": No address associated with hostname
at java.net.Inet6AddressImpl.lookupHostByName(Inet6AddressImpl.java:156)
at java.net.Inet6AddressImpl.lookupAllHostAddr(Inet6AddressImpl.java:103)
at java.net.InetAddress.getAllByName(InetAddress.java:1152)
at okhttp3.Dns$Companion$DnsSystem.lookup(Dns.kt:49)
at okhttp3.OkHttpClientTestRule$Companion$SINGLE_INET_ADDRESS_DNS$1.lookup(OkHttpClientTestRule.kt:263)
at okhttp3.internal.connection.RouteSelector.resetNextInetSocketAddress(RouteSelector.kt:164)
at okhttp3.internal.connection.RouteSelector.nextProxy(RouteSelector.kt:129)
at okhttp3.internal.connection.RouteSelector.next(RouteSelector.kt:71)
at okhttp3.internal.connection.ExchangeFinder.findConnection(ExchangeFinder.kt:213)
at okhttp3.internal.connection.ExchangeFinder.findHealthyConnection(ExchangeFinder.kt:108)
at okhttp3.internal.connection.ExchangeFinder.find(ExchangeFinder.kt:76)
at okhttp3.internal.connection.RealCall.initExchange$okhttp(RealCall.kt:245)
at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.kt:32)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:100)
at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.kt:96)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:100)
at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.kt:83)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:100)
at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.kt:76)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:100)
at okhttp3.internal.connection.RealCall.getResponseWithInterceptorChain$okhttp(RealCall.kt:197)
at okhttp3.internal.connection.RealCall.execute(RealCall.kt:148)
at okhttp.android.test.OkHttpTest.testHttpRequestBlocked(OkHttpTest.kt:276)
at java.lang.reflect.Method.invoke(Native Method)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at okhttp3.OkHttpClientTestRule$apply$1.evaluate(OkHttpClientTestRule.kt:184)
at okhttp3.testing.PlatformRule$apply$1.evaluate(PlatformRule.kt:70)
at org.junit.rules.ExternalResource$1.evaluate(ExternalResource.java:54)
at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
at androidx.test.ext.junit.runners.AndroidJUnit4.run(AndroidJUnit4.java:104)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:27)
at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
at androidx.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
at androidx.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:392)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:2189)
Caused by: android.system.GaiException: android_getaddrinfo failed: EAI_NODATA (No address associated with hostname)
at libcore.io.Linux.android_getaddrinfo(Native Method)
at libcore.io.ForwardingOs.android_getaddrinfo(ForwardingOs.java:74)
at libcore.io.BlockGuardOs.android_getaddrinfo(BlockGuardOs.java:200)
at libcore.io.ForwardingOs.android_getaddrinfo(ForwardingOs.java:74)
at java.net.Inet6AddressImpl.lookupHostByName(Inet6AddressImpl.java:135)
... 57 more

[yschimke]

Also relevant https://github.com/grpc/grpc-java/blob/master/documentation/android-channel-builder.md https://github.com/grpc/grpc-java/blob/b06f888615b01a4d04a2429855e06fde62030064/android/src/main/java/io/grpc/android/AndroidChannelBuilder.java