Move rate limit interceptor logic to module (#1100)

lib/ratelimit/build.gradle

@@ -0,0 +1,29 @@
+apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
+
+android {
+    compileSdkVersion 27
+    buildToolsVersion '28.0.3'
+
+    defaultConfig {
+        minSdkVersion 16
+        targetSdkVersion 27
+        versionCode 1
+        versionName '1.0.0'
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+        }
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    compileOnly "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    compileOnly 'com.squareup.okhttp3:okhttp:3.10.0'
+}

lib/ratelimit/src/main/AndroidManifest.xml

@@ -0,0 +1,3 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="eu.kanade.tachiyomi.lib.ratelimit">
+</manifest>

lib/ratelimit/src/main/java/eu/kanade/tachiyomi/lib/ratelimit/RateLimitInterceptor.kt

@@ -0,0 +1,58 @@
+package eu.kanade.tachiyomi.lib.ratelimit
+
+import android.os.SystemClock
+import okhttp3.Interceptor
+import okhttp3.Response
+import java.util.concurrent.TimeUnit
+
+/**
+ * An OkHttp interceptor that handles rate limiting.
+ *
+ * Examples:
+ *
+ * permits = 5,  period = 1, unit = seconds  =>  5 requests per second
+ * permits = 10, period = 2, unit = minutes  =>  10 requests per 2 minutes
+ *
+ * @param permits {Int}   Number of requests allowed within a period of units.
+ * @param period {Long}   The limiting duration. Defaults to 1.
+ * @param unit {TimeUnit} The unit of time for the period. Defaults to seconds.
+ */
+class RateLimitInterceptor(
+        private val permits: Int,
+        private val period: Long = 1,
+        private val unit: TimeUnit = TimeUnit.SECONDS) : Interceptor {
+
+    private val requestQueue = ArrayList<Long>(permits)
+    private val rateLimitMillis = unit.toMillis(period)
+
+    override fun intercept(chain: Interceptor.Chain): Response {
+        synchronized(requestQueue) {
+            val now = SystemClock.elapsedRealtime()
+            val waitTime = if (requestQueue.size < permits) {
+                0
+            } else {
+                val oldestReq = requestQueue[0]
+                val newestReq = requestQueue[permits - 1]
+
+                if (newestReq - oldestReq > rateLimitMillis) {
+                    0
+                } else {
+                    oldestReq + rateLimitMillis - now // Remaining time
+                }
+            }
+
+            if (requestQueue.size == permits) {
+                requestQueue.removeAt(0)
+            }
+            if (waitTime > 0) {
+                requestQueue.add(now + waitTime)
+                Thread.sleep(waitTime) // Sleep inside synchronized to pause queued requests
+            } else {
+                requestQueue.add(now)
+            }
+        }
+
+        return chain.proceed(chain.request())
+    }
+
+}

settings.gradle

@@ -7,5 +7,7 @@ new File(rootDir, "src").eachDir { dir ->
 }
 include ':duktape-stub'
 include ':preference-stub'
+include ':lib-ratelimit'
 project(':duktape-stub').projectDir = new File("lib/duktape-stub")
-project(':preference-stub').projectDir = new File("lib/preference-stub")
+project(':preference-stub').projectDir = new File("lib/preference-stub")
+project(':lib-ratelimit').projectDir = new File("lib/ratelimit")

src/all/mangadex/build.gradle

@@ -5,11 +5,12 @@ ext {
     appName = 'Tachiyomi: MangaDex'
     pkgNameSuffix = 'all.mangadex'
     extClass = '.MangadexFactory'
-    extVersionCode = 56
+    extVersionCode = 57
     libVersion = '1.2'
 }
 
 dependencies {
+    implementation project(':lib-ratelimit')
     compileOnly project(':preference-stub')
     compileOnly 'com.google.code.gson:gson:2.8.2'
     compileOnly 'com.github.salomonbrys.kotson:kotson:2.5.0'

src/all/mangadex/src/eu/kanade/tachiyomi/extension/all/mangadex/Mangadex.kt

@@ -2,7 +2,6 @@ package eu.kanade.tachiyomi.extension.all.mangadex
 
 import android.app.Application
 import android.content.SharedPreferences
-import android.os.SystemClock
 import android.support.v7.preference.ListPreference
 import android.support.v7.preference.PreferenceScreen
 import com.github.salomonbrys.kotson.forEach
@@ -16,6 +15,7 @@ import com.github.salomonbrys.kotson.string
 import com.google.gson.JsonElement
 import com.google.gson.JsonObject
 import com.google.gson.JsonParser
+import eu.kanade.tachiyomi.lib.ratelimit.RateLimitInterceptor
 import eu.kanade.tachiyomi.network.GET
 import eu.kanade.tachiyomi.network.asObservableSuccess
 import eu.kanade.tachiyomi.source.ConfigurableSource
@@ -28,7 +28,6 @@ import eu.kanade.tachiyomi.source.model.SManga
 import eu.kanade.tachiyomi.source.online.ParsedHttpSource
 import okhttp3.Headers
 import okhttp3.HttpUrl
-import okhttp3.Interceptor
 import okhttp3.OkHttpClient
 import okhttp3.Request
 import okhttp3.Response
@@ -57,37 +56,7 @@ open class Mangadex(override val lang: String, private val internalLang: String,
         Injekt.get<Application>().getSharedPreferences("source_$id", 0x0000)
     }
 
-    private val requestsPerSecond = 4
-    private val lastRequests = ArrayList<Long>(requestsPerSecond)
-    private val rateLimitInterceptor = Interceptor {
-        synchronized(this) {
-            val now = SystemClock.elapsedRealtime()
-            val waitTime = if (lastRequests.size < requestsPerSecond) {
-                0
-            } else {
-                val oldestReq = lastRequests[0]
-                val newestReq = lastRequests[requestsPerSecond - 1]
-
-                if (newestReq - oldestReq > 1000) {
-                    0
-                } else {
-                    oldestReq + 1000 - now // Remaining time for the next second
-                }
-            }
-
-            if (lastRequests.size == requestsPerSecond) {
-                lastRequests.removeAt(0)
-            }
-            if (waitTime > 0) {
-                lastRequests.add(now + waitTime)
-                Thread.sleep(waitTime) // Sleep inside synchronized to pause queued requests
-            } else {
-                lastRequests.add(now)
-            }
-        }
-
-        it.proceed(it.request())
-    }
+    private val rateLimitInterceptor = RateLimitInterceptor(4)
 
     override val client: OkHttpClient = network.cloudflareClient.newBuilder()
             .addNetworkInterceptor(rateLimitInterceptor)