From e77478b13e819b2af2579d4b85a0bb168bb0c56d Mon Sep 17 00:00:00 2001
From: InsanusMokrassar <ovsyannikov.alexey95@gmail.com>
Date: Thu, 24 Jan 2019 10:35:38 +0800
Subject: [PATCH] RequestLimiter

---
 CHANGELOG                                     |  1 +
 .../bot/settings/limiters/EmptyLimiter.kt     |  5 ++
 .../bot/settings/limiters/PowLimiter.kt       | 73 +++++++++++++++++++
 .../bot/settings/limiters/RequestLimiter.kt   |  8 ++
 4 files changed, 87 insertions(+)
 create mode 100644 src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/EmptyLimiter.kt
 create mode 100644 src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/PowLimiter.kt
 create mode 100644 src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/RequestLimiter.kt

diff --git a/CHANGELOG b/CHANGELOG
index 0e9898854b..c8b8b4c1ab 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -49,3 +49,4 @@
 `com.github.insanusmokrassar.TelegramBotAPI.bot.Ktor` package
 * Replace `ProxySettings` data class in `settings` package, deprecate old link
 * `BaseRequestsExecutor` now have no it's own scope
+* Add `RequestLimiter` and base realisations
diff --git a/src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/EmptyLimiter.kt b/src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/EmptyLimiter.kt
new file mode 100644
index 0000000000..c0a24f1885
--- /dev/null
+++ b/src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/EmptyLimiter.kt
@@ -0,0 +1,5 @@
+package com.github.insanusmokrassar.TelegramBotAPI.bot.settings.limiters
+
+object EmptyLimiter : RequestLimiter {
+    override suspend fun <T> limit(block: suspend () -> T): T = block()
+}
diff --git a/src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/PowLimiter.kt b/src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/PowLimiter.kt
new file mode 100644
index 0000000000..d20bbc194d
--- /dev/null
+++ b/src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/PowLimiter.kt
@@ -0,0 +1,73 @@
+package com.github.insanusmokrassar.TelegramBotAPI.bot.settings.limiters
+
+import kotlinx.coroutines.*
+import kotlinx.coroutines.channels.Channel
+import kotlinx.serialization.Optional
+import kotlinx.serialization.Serializable
+import java.util.concurrent.Executors
+import kotlin.coroutines.*
+
+private sealed class RequestEvent
+private class AddRequest(
+    val continuation: Continuation<Long>
+) : RequestEvent()
+private object CompleteRequest : RequestEvent()
+
+@Serializable
+data class PowLimiter(
+    @Optional
+    private val minAwaitTime: Long = 0L,
+    @Optional
+    private val maxAwaitTime: Long = 10000L,
+    @Optional
+    private val powValue: Double = 4.0,
+    @Optional
+    private val powK: Double = 0.0016
+) : RequestLimiter {
+    private val scope = CoroutineScope(
+        Executors.newFixedThreadPool(3).asCoroutineDispatcher()
+    )
+    private val eventsChannel = Channel<RequestEvent>(Channel.UNLIMITED)
+    private val awaitTimeRange = minAwaitTime .. maxAwaitTime
+
+    init {
+        scope.launch {
+            var requestsInWork: Double = 0.0
+            for (event in eventsChannel) {
+                when (event) {
+                    is AddRequest -> {
+                        val awaitTime = ((Math.pow(requestsInWork, powValue) * powK) * 1000L).toLong()
+                        requestsInWork++
+
+                        event.continuation.resume(
+                            if (awaitTime in awaitTimeRange) {
+                                awaitTime
+                            } else {
+                                if (awaitTime < minAwaitTime) {
+                                    minAwaitTime
+                                } else {
+                                    maxAwaitTime
+                                }
+                            }
+                        )
+                    }
+                    is CompleteRequest -> requestsInWork--
+                }
+            }
+        }
+    }
+
+    override suspend fun <T> limit(
+        block: suspend () -> T
+    ): T {
+        val delayMillis = suspendCoroutine<Long> {
+            scope.launch { eventsChannel.send(AddRequest(it)) }
+        }
+        delay(delayMillis)
+        return try {
+            block()
+        } finally {
+            eventsChannel.send(CompleteRequest)
+        }
+    }
+}
diff --git a/src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/RequestLimiter.kt b/src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/RequestLimiter.kt
new file mode 100644
index 0000000000..8abc707151
--- /dev/null
+++ b/src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/bot/settings/limiters/RequestLimiter.kt
@@ -0,0 +1,8 @@
+package com.github.insanusmokrassar.TelegramBotAPI.bot.settings.limiters
+
+interface RequestLimiter {
+    /**
+     * Use limit for working of block (like delay between or after, for example)
+     */
+    suspend fun <T> limit(block: suspend () -> T): T
+}