jvmMain.okhttp3.internal.connection.FastFallbackExchangeFinder.kt Maven / Gradle / Ivy
/*
* Copyright (C) 2022 Square, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package okhttp3.internal.connection
import java.io.IOException
import java.util.concurrent.LinkedBlockingDeque
import java.util.concurrent.TimeUnit
import okhttp3.internal.concurrent.Task
import okhttp3.internal.concurrent.TaskRunner
import okhttp3.internal.connection.RoutePlanner.Plan
import okhttp3.internal.okHttpName
/**
* Speculatively connects to each IP address of a target address, returning as soon as one of them
* connects successfully. This kicks off new attempts every 250 ms until a connect succeeds.
*/
internal class FastFallbackExchangeFinder(
private val routePlanner: RoutePlanner,
private val taskRunner: TaskRunner,
) {
private val connectDelayMillis = 250L
/** Plans currently being connected, and that will later be added to [connectResults]. */
private var connectsInFlight = mutableListOf()
/**
* Results are posted here as they occur. The find job is done when either one plan completes
* successfully or all plans fail.
*/
private val connectResults = taskRunner.backend.decorate(LinkedBlockingDeque())
/** Exceptions accumulate here. */
private var firstException: IOException? = null
/** True until we've launched all the connects we'll ever launch. */
private var morePlansExist = true
fun find(): RealConnection {
try {
while (morePlansExist || connectsInFlight.isNotEmpty()) {
if (routePlanner.isCanceled()) throw IOException("Canceled")
launchConnect()
val connection = awaitConnection()
if (connection != null) return connection
morePlansExist = morePlansExist && routePlanner.hasMoreRoutes()
}
throw firstException!!
} finally {
for (plan in connectsInFlight) {
plan.cancel()
}
}
}
private fun launchConnect() {
if (!morePlansExist) return
val plan = try {
routePlanner.plan()
} catch (e: IOException) {
trackFailure(e)
return
}
connectsInFlight += plan
// Already connected? Enqueue the result immediately.
if (plan.isConnected) {
connectResults.put(ConnectResult(plan, null))
return
}
// Connect asynchronously.
val taskName = "$okHttpName connect ${routePlanner.address.url.redact()}"
taskRunner.newQueue().schedule(object : Task(taskName) {
override fun runOnce(): Long {
try {
plan.connect()
connectResults.put(ConnectResult(plan, null))
} catch (e: Throwable) {
connectResults.put(ConnectResult(plan, e))
}
return -1L
}
})
}
private fun awaitConnection(): RealConnection? {
if (connectsInFlight.isEmpty()) return null
val completed = connectResults.poll(connectDelayMillis, TimeUnit.MILLISECONDS) ?: return null
connectsInFlight.remove(completed.plan)
val exception = completed.throwable
if (exception is IOException) {
trackFailure(exception)
return null
} else if (exception != null) {
throw exception
}
return completed.plan.handleSuccess()
}
private fun trackFailure(exception: IOException) {
routePlanner.trackFailure(exception)
if (firstException == null) {
firstException = exception
} else {
firstException!!.addSuppressed(exception)
}
}
private class ConnectResult(
val plan: Plan,
val throwable: Throwable?,
)
}