├── .gitignore ├── CHANGELOG.md ├── LICENSE.txt ├── README.md ├── build.gradle ├── gradle └── wrapper │ ├── gradle-wrapper.jar │ └── gradle-wrapper.properties ├── gradlew ├── gradlew.bat └── src ├── main └── java │ └── com │ └── zhuinden │ └── commandqueue │ └── CommandQueue.java └── test └── java └── com └── zhuinden └── commandqueue ├── CommandQueueMockitoTest.java ├── CommandQueueTest.java └── TestSuite.java /.gitignore: -------------------------------------------------------------------------------- 1 | *.class 2 | build/ 3 | .gradle 4 | .idea 5 | *.jar 6 | *.aar 7 | *.war 8 | !gradle-wrapper.jar 9 | -------------------------------------------------------------------------------- /CHANGELOG.md: -------------------------------------------------------------------------------- 1 | # Change log 2 | 3 | -Command Queue 1.2.0 (2020-12-24) 4 | -------------------------------- 5 | 6 | - CHANGE: Added proper thread-confinement checks to ensure proper thread-safe access to CommandQueue. 7 | 8 | - UPDATE: make pure-JVM library. 9 | 10 | -Command Queue 1.1.0 (2020-02-29) 11 | -------------------------------- 12 | 13 | - CHANGE: Remove dependency on `android.support.annotation.*`. With that, there should be no dependency from the library on either `android.support.*` or `androidx.*`. 14 | 15 | Replaced it using `javax.annotation.Nullable` and `javax.annotation.Nonnull` provided by `api("com.google.code.findbugs:jsr305:3.0.2")`. 16 | 17 | With these changes, Jetifier should no longer be needed when using Command-Queue. 18 | 19 | -Command Queue 1.0.0 (2019-09-27) 20 | -------------------------------- 21 | - No changes. Version bump to 1.0.0. 22 | 23 | -Command Queue 0.1.3 (2018-12-10) 24 | -------------------------------- 25 | - Remove: `CommandQueue(boolean distinctOnly)`. 26 | 27 | - Add `CommandQueue.Builder` to configure the created command queue. 28 | 29 | - Add `CommandQueue.Builder.distinctOnly()`, which instructs the command queue not to send the event if the new event is content-equal to the previous event. 30 | 31 | - Add `CommandQueue.Builder.limit(int)`, which instructs the command queue to drop new events if the queue is already "full". 32 | 33 | -Command Queue 0.1.1 (2018-10-03) 34 | -------------------------------- 35 | - Fix: Calling `setReceiver(Receiver)` inside a `receiveCommand` block will no longer "freeze" the queue. 36 | 37 | -Command Queue 0.1.0 (2018-10-03) 38 | -------------------------------- 39 | - Add `setPaused(boolean)` to temporarily freeze the queue even if receiver is available. 40 | 41 | -Command Queue 0.0.3 (2018-09-16) 42 | -------------------------------- 43 | - Fix possible edge case of a receiver setting a different receiver in the `receiveCommand` block. 44 | 45 | - Add sample code. 46 | 47 | -Command Queue 0.0.2 (2018-09-16) 48 | -------------------------------- 49 | - Add `hasReceiver()`. 50 | 51 | - Fix that emitting an event inside the receiver block could be executed in the wrong order. 52 | 53 | -Command Queue 0.0.1 (2018-09-13) 54 | -------------------------------- 55 | - Initial Release. -------------------------------------------------------------------------------- /LICENSE.txt: -------------------------------------------------------------------------------- 1 | 2 | Apache License 3 | Version 2.0, January 2004 4 | http://www.apache.org/licenses/ 5 | 6 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 7 | 8 | 1. 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We also recommend that a 186 | file or class name and description of purpose be included on the 187 | same "printed page" as the copyright notice for easier 188 | identification within third-party archives. 189 | 190 | Copyright [yyyy] [name of copyright owner] 191 | 192 | Licensed under the Apache License, Version 2.0 (the "License"); 193 | you may not use this file except in compliance with the License. 194 | You may obtain a copy of the License at 195 | 196 | http://www.apache.org/licenses/LICENSE-2.0 197 | 198 | Unless required by applicable law or agreed to in writing, software 199 | distributed under the License is distributed on an "AS IS" BASIS, 200 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 201 | See the License for the specific language governing permissions and 202 | limitations under the License. -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Command Queue 2 | 3 | The command queue lets you register a single receiver, and while there is no receiver, the commands are enqueued. 4 | 5 | ## Using Command Queue 6 | 7 | In order to use Command Queue, you need to add jitpack to your project root gradle: 8 | 9 | buildscript { 10 | repositories { 11 | // ... 12 | maven { url "https://jitpack.io" } 13 | } 14 | // ... 15 | } 16 | allprojects { 17 | repositories { 18 | // ... 19 | maven { url "https://jitpack.io" } 20 | } 21 | // ... 22 | } 23 | 24 | In newer projects, you need to also update the `settings.gradle` file's `dependencyResolutionManagement` block: 25 | 26 | ``` 27 | dependencyResolutionManagement { 28 | repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS) 29 | repositories { 30 | google() 31 | mavenCentral() 32 | maven { url 'https://jitpack.io' } // <-- 33 | jcenter() // Warning: this repository is going to shut down soon 34 | } 35 | } 36 | ``` 37 | 38 | 39 | 40 | and add the dependency to your module level gradle. 41 | 42 | implementation 'com.github.Zhuinden:command-queue:1.2.0' 43 | 44 | ## Sample code 45 | 46 | See sample [here](https://github.com/Zhuinden/command-queue/tree/302edf809545e912c38db0865164f418d24f38d0/command-queue-sample). 47 | 48 | Please note that CommandQueue is used as internal implementation detail for both `EventEmitter` and `LiveEvent`, if those suit your needs better. 49 | 50 | ## License 51 | 52 | Copyright 2018 Gabor Varadi 53 | 54 | Licensed under the Apache License, Version 2.0 (the "License"); 55 | you may not use this file except in compliance with the License. 56 | You may obtain a copy of the License at 57 | 58 | http://www.apache.org/licenses/LICENSE-2.0 59 | 60 | Unless required by applicable law or agreed to in writing, software 61 | distributed under the License is distributed on an "AS IS" BASIS, 62 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 63 | See the License for the specific language governing permissions and 64 | limitations under the License. 65 | -------------------------------------------------------------------------------- /build.gradle: -------------------------------------------------------------------------------- 1 | buildscript { 2 | repositories { 3 | mavenCentral() 4 | jcenter() 5 | } 6 | } 7 | 8 | apply plugin: 'java-library' 9 | apply plugin: 'maven-publish' 10 | 11 | sourceCompatibility = 1.7 // java 7 12 | targetCompatibility = 1.7 13 | 14 | repositories { 15 | mavenCentral() 16 | jcenter() 17 | } 18 | 19 | dependencies { 20 | api "com.google.code.findbugs:jsr305:3.0.2" 21 | 22 | testImplementation "junit:junit:4.13.1" 23 | testImplementation "org.assertj:assertj-core:3.16.1" 24 | testImplementation "org.mockito:mockito-core:2.23.0" 25 | } 26 | 27 | task sourcesJar(type: Jar, dependsOn: classes) { 28 | classifier = 'sources' 29 | from sourceSets.main.allSource 30 | } 31 | 32 | task javadocJar(type: Jar, dependsOn: javadoc) { 33 | classifier = 'javadoc' 34 | from javadoc.destinationDir 35 | } 36 | 37 | artifacts { 38 | archives sourcesJar 39 | archives javadocJar 40 | } 41 | 42 | publishing { 43 | publications { 44 | maven(MavenPublication) { 45 | groupId = 'com.github.Zhuinden' 46 | artifactId = 'command-queue' 47 | version = '1.2.0' 48 | 49 | from components.java 50 | artifact sourcesJar 51 | } 52 | } 53 | } 54 | 55 | wrapper { 56 | gradleVersion = "6.5" 57 | distributionType = Wrapper.DistributionType.ALL 58 | } -------------------------------------------------------------------------------- /gradle/wrapper/gradle-wrapper.jar: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/Zhuinden/command-queue/5c73bde718ebdbb575aa4d63840540588d9a08c0/gradle/wrapper/gradle-wrapper.jar -------------------------------------------------------------------------------- /gradle/wrapper/gradle-wrapper.properties: -------------------------------------------------------------------------------- 1 | distributionBase=GRADLE_USER_HOME 2 | distributionPath=wrapper/dists 3 | distributionUrl=https\://services.gradle.org/distributions/gradle-6.1.1-all.zip 4 | zipStoreBase=GRADLE_USER_HOME 5 | zipStorePath=wrapper/dists 6 | -------------------------------------------------------------------------------- /gradlew: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env sh 2 | 3 | ############################################################################## 4 | ## 5 | ## Gradle start up script for UN*X 6 | ## 7 | ############################################################################## 8 | 9 | # Attempt to set APP_HOME 10 | # Resolve links: $0 may be a link 11 | PRG="$0" 12 | # Need this for relative symlinks. 13 | while [ -h "$PRG" ] ; do 14 | ls=`ls -ld "$PRG"` 15 | link=`expr "$ls" : '.*-> $.*$$'` 16 | if expr "$link" : '/.*' > /dev/null; then 17 | PRG="$link" 18 | else 19 | PRG=`dirname "$PRG"`"/$link" 20 | fi 21 | done 22 | SAVED="`pwd`" 23 | cd "`dirname \"$PRG\"`/" >/dev/null 24 | APP_HOME="`pwd -P`" 25 | cd "$SAVED" >/dev/null 26 | 27 | APP_NAME="Gradle" 28 | APP_BASE_NAME=`basename "$0"` 29 | 30 | # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. 31 | DEFAULT_JVM_OPTS='"-Xmx64m"' 32 | 33 | # Use the maximum available, or set MAX_FD != -1 to use that value. 34 | MAX_FD="maximum" 35 | 36 | warn () { 37 | echo "$*" 38 | } 39 | 40 | die () { 41 | echo 42 | echo "$*" 43 | echo 44 | exit 1 45 | } 46 | 47 | # OS specific support (must be 'true' or 'false'). 48 | cygwin=false 49 | msys=false 50 | darwin=false 51 | nonstop=false 52 | case "`uname`" in 53 | CYGWIN* ) 54 | cygwin=true 55 | ;; 56 | Darwin* ) 57 | darwin=true 58 | ;; 59 | MINGW* ) 60 | msys=true 61 | ;; 62 | NONSTOP* ) 63 | nonstop=true 64 | ;; 65 | esac 66 | 67 | CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar 68 | 69 | # Determine the Java command to use to start the JVM. 70 | if [ -n "$JAVA_HOME" ] ; then 71 | if [ -x "$JAVA_HOME/jre/sh/java" ] ; then 72 | # IBM's JDK on AIX uses strange locations for the executables 73 | JAVACMD="$JAVA_HOME/jre/sh/java" 74 | else 75 | JAVACMD="$JAVA_HOME/bin/java" 76 | fi 77 | if [ ! -x "$JAVACMD" ] ; then 78 | die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME 79 | 80 | Please set the JAVA_HOME variable in your environment to match the 81 | location of your Java installation." 82 | fi 83 | else 84 | JAVACMD="java" 85 | which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 86 | 87 | Please set the JAVA_HOME variable in your environment to match the 88 | location of your Java installation." 89 | fi 90 | 91 | # Increase the maximum file descriptors if we can. 92 | if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then 93 | MAX_FD_LIMIT=`ulimit -H -n` 94 | if [ $? -eq 0 ] ; then 95 | if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then 96 | MAX_FD="$MAX_FD_LIMIT" 97 | fi 98 | ulimit -n $MAX_FD 99 | if [ $? -ne 0 ] ; then 100 | warn "Could not set maximum file descriptor limit: $MAX_FD" 101 | fi 102 | else 103 | warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT" 104 | fi 105 | fi 106 | 107 | # For Darwin, add options to specify how the application appears in the dock 108 | if $darwin; then 109 | GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\"" 110 | fi 111 | 112 | # For Cygwin, switch paths to Windows format before running java 113 | if $cygwin ; then 114 | APP_HOME=`cygpath --path --mixed "$APP_HOME"` 115 | CLASSPATH=`cygpath --path --mixed "$CLASSPATH"` 116 | JAVACMD=`cygpath --unix "$JAVACMD"` 117 | 118 | # We build the pattern for arguments to be converted via cygpath 119 | ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null` 120 | SEP="" 121 | for dir in $ROOTDIRSRAW ; do 122 | ROOTDIRS="$ROOTDIRS$SEP$dir" 123 | SEP="|" 124 | done 125 | OURCYGPATTERN="(^($ROOTDIRS))" 126 | # Add a user-defined pattern to the cygpath arguments 127 | if [ "$GRADLE_CYGPATTERN" != "" ] ; then 128 | OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)" 129 | fi 130 | # Now convert the arguments - kludge to limit ourselves to /bin/sh 131 | i=0 132 | for arg in "$@" ; do 133 | CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -` 134 | CHECK2=`echo "$arg"|egrep -c "^-"` ### Determine if an option 135 | 136 | if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then ### Added a condition 137 | eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"` 138 | else 139 | eval `echo args$i`="\"$arg\"" 140 | fi 141 | i=$((i+1)) 142 | done 143 | case $i in 144 | (0) set -- ;; 145 | (1) set -- "$args0" ;; 146 | (2) set -- "$args0" "$args1" ;; 147 | (3) set -- "$args0" "$args1" "$args2" ;; 148 | (4) set -- "$args0" "$args1" "$args2" "$args3" ;; 149 | (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;; 150 | (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;; 151 | (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;; 152 | (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;; 153 | (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;; 154 | esac 155 | fi 156 | 157 | # Escape application args 158 | save () { 159 | for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done 160 | echo " " 161 | } 162 | APP_ARGS=$(save "$@") 163 | 164 | # Collect all arguments for the java command, following the shell quoting and substitution rules 165 | eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS" 166 | 167 | # by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong 168 | if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then 169 | cd "$(dirname "$0")" 170 | fi 171 | 172 | exec "$JAVACMD" "$@" 173 | -------------------------------------------------------------------------------- /gradlew.bat: -------------------------------------------------------------------------------- 1 | @if "%DEBUG%" == "" @echo off 2 | @rem ########################################################################## 3 | @rem 4 | @rem Gradle startup script for Windows 5 | @rem 6 | @rem ########################################################################## 7 | 8 | @rem Set local scope for the variables with windows NT shell 9 | if "%OS%"=="Windows_NT" setlocal 10 | 11 | set DIRNAME=%~dp0 12 | if "%DIRNAME%" == "" set DIRNAME=. 13 | set APP_BASE_NAME=%~n0 14 | set APP_HOME=%DIRNAME% 15 | 16 | @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. 17 | set DEFAULT_JVM_OPTS="-Xmx64m" 18 | 19 | @rem Find java.exe 20 | if defined JAVA_HOME goto findJavaFromJavaHome 21 | 22 | set JAVA_EXE=java.exe 23 | %JAVA_EXE% -version >NUL 2>&1 24 | if "%ERRORLEVEL%" == "0" goto init 25 | 26 | echo. 27 | echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 28 | echo. 29 | echo Please set the JAVA_HOME variable in your environment to match the 30 | echo location of your Java installation. 31 | 32 | goto fail 33 | 34 | :findJavaFromJavaHome 35 | set JAVA_HOME=%JAVA_HOME:"=% 36 | set JAVA_EXE=%JAVA_HOME%/bin/java.exe 37 | 38 | if exist "%JAVA_EXE%" goto init 39 | 40 | echo. 41 | echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 42 | echo. 43 | echo Please set the JAVA_HOME variable in your environment to match the 44 | echo location of your Java installation. 45 | 46 | goto fail 47 | 48 | :init 49 | @rem Get command-line arguments, handling Windows variants 50 | 51 | if not "%OS%" == "Windows_NT" goto win9xME_args 52 | 53 | :win9xME_args 54 | @rem Slurp the command line arguments. 55 | set CMD_LINE_ARGS= 56 | set _SKIP=2 57 | 58 | :win9xME_args_slurp 59 | if "x%~1" == "x" goto execute 60 | 61 | set CMD_LINE_ARGS=%* 62 | 63 | :execute 64 | @rem Setup the command line 65 | 66 | set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar 67 | 68 | @rem Execute Gradle 69 | "%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS% 70 | 71 | :end 72 | @rem End local scope for the variables with windows NT shell 73 | if "%ERRORLEVEL%"=="0" goto mainEnd 74 | 75 | :fail 76 | rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of 77 | rem the _cmd.exe /c_ return code! 78 | if not "" == "%GRADLE_EXIT_CONSOLE%" exit 1 79 | exit /b 1 80 | 81 | :mainEnd 82 | if "%OS%"=="Windows_NT" endlocal 83 | 84 | :omega 85 | -------------------------------------------------------------------------------- /src/main/java/com/zhuinden/commandqueue/CommandQueue.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 Gabor Varadi 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.zhuinden.commandqueue; 17 | 18 | import java.util.concurrent.ConcurrentLinkedQueue; 19 | 20 | import javax.annotation.Nonnull; 21 | import javax.annotation.Nullable; 22 | 23 | /** 24 | * A class that can be used to send events, and events are enqueued while there is no observer. 25 | * Allows only a single receiver at a time. Enqueued events are emitted on registration. 26 | * 27 | * @param the type of the event 28 | */ 29 | public class CommandQueue { 30 | private final long threadId = Thread.currentThread().getId(); 31 | 32 | private final ConcurrentLinkedQueue queuedEvents = new ConcurrentLinkedQueue(); 33 | private boolean paused; 34 | private boolean distinctOnly; 35 | private int limit = -1; 36 | 37 | public CommandQueue() { 38 | } 39 | 40 | public static class Builder { 41 | private boolean distinctOnly = false; 42 | 43 | private int limit = -1; 44 | 45 | public Builder distinctOnly() { 46 | this.distinctOnly = true; 47 | return this; 48 | } 49 | 50 | public Builder limit(int limit) { 51 | this.limit = limit; 52 | return this; 53 | } 54 | 55 | public CommandQueue build() { 56 | CommandQueue commandQueue = new CommandQueue(); 57 | commandQueue.distinctOnly = distinctOnly; 58 | commandQueue.limit = limit; 59 | return commandQueue; 60 | } 61 | } 62 | 63 | /** 64 | * The receiver receives commands when it is set. 65 | * 66 | * @param the type of the event 67 | */ 68 | public interface Receiver { 69 | void receiveCommand(@Nonnull T command); 70 | } 71 | 72 | private Receiver receiver; 73 | 74 | /** 75 | * Returns if the command queue has a receiver. 76 | * 77 | * @return whether there is a receiver 78 | */ 79 | public boolean hasReceiver() { 80 | verifyCurrentThread(); 81 | return receiver != null; 82 | } 83 | 84 | private boolean isEmittingEvent = false; 85 | 86 | private boolean canEmitEvents() { 87 | return receiver != null && !isEmittingEvent && !paused; 88 | } 89 | 90 | private T previouslyEmittedEvent; 91 | 92 | private void emitEvents(@Nonnull final Receiver receiver) { 93 | while(canEmitEvents() && !queuedEvents.isEmpty() && this.receiver == receiver) { 94 | T event = queuedEvents.poll(); 95 | isEmittingEvent = true; 96 | sendCommandToReceiver(receiver, event); 97 | isEmittingEvent = false; 98 | } 99 | 100 | if(this.receiver != receiver) { 101 | emitEvents(this.receiver); 102 | } 103 | } 104 | 105 | private void sendCommandToReceiver(@Nonnull Receiver receiver, @Nonnull T event) { 106 | T previousEvent = previouslyEmittedEvent; 107 | if(previousEvent != null && event.equals(previousEvent) && distinctOnly) { 108 | return; // don't send duplicate commands if distinct only 109 | } 110 | this.previouslyEmittedEvent = event; 111 | receiver.receiveCommand(event); 112 | } 113 | 114 | /** 115 | * Sets the receiver. If there are any enqueued events, the receiver will receive them when set. 116 | * 117 | * @param receiver the event receiver 118 | */ 119 | public void setReceiver(@Nullable final Receiver receiver) { 120 | verifyCurrentThread(); 121 | 122 | this.receiver = receiver; 123 | 124 | if(receiver != null) { 125 | emitEvents(receiver); 126 | } 127 | } 128 | 129 | /** 130 | * Sets whether the queue is paused. The paused queue emits only when it is unpaused, and a receiver is available. 131 | * 132 | * @param paused whether the queue is paused 133 | */ 134 | public void setPaused(boolean paused) { 135 | verifyCurrentThread(); 136 | 137 | final boolean wasPaused = this.paused; 138 | 139 | this.paused = paused; 140 | 141 | if(wasPaused && !paused) { 142 | final Receiver currentReceiver = receiver; 143 | if(currentReceiver != null) { 144 | emitEvents(currentReceiver); 145 | } 146 | } 147 | } 148 | 149 | /** 150 | * Removes the currently set receiver. 151 | */ 152 | public void detachReceiver() { 153 | verifyCurrentThread(); 154 | 155 | this.receiver = null; 156 | } 157 | 158 | /** 159 | * Sends the event to the receiver. If there is no receiver, then the event is enqueued until a new receiver is set. 160 | * 161 | * @param event the event 162 | */ 163 | public void sendEvent(@Nonnull final T event) { 164 | verifyCurrentThread(); 165 | 166 | //noinspection ConstantConditions 167 | if(event == null) { 168 | throw new IllegalArgumentException("Null value is not allowed as an event"); 169 | } 170 | if(!canEmitEvents()) { 171 | if(limit == -1 || queuedEvents.size() < limit) { // drop new events that don't fit the queue 172 | queuedEvents.add(event); 173 | } 174 | } else { 175 | sendCommandToReceiver(receiver, event); 176 | } 177 | } 178 | 179 | private void verifyCurrentThread() { 180 | if(threadId != Thread.currentThread().getId()) { 181 | throw new IllegalStateException( 182 | "A command queue can only be accessed on the thread where it was created."); 183 | } 184 | } 185 | } -------------------------------------------------------------------------------- /src/test/java/com/zhuinden/commandqueue/CommandQueueMockitoTest.java: -------------------------------------------------------------------------------- 1 | package com.zhuinden.commandqueue; 2 | 3 | import org.junit.Assert; 4 | import org.junit.Before; 5 | import org.junit.Test; 6 | import org.junit.runner.RunWith; 7 | import org.mockito.ArgumentCaptor; 8 | import org.mockito.Mock; 9 | import org.mockito.junit.MockitoJUnitRunner; 10 | 11 | import java.util.List; 12 | 13 | import static org.hamcrest.CoreMatchers.is; 14 | import static org.mockito.Mockito.times; 15 | import static org.mockito.Mockito.verify; 16 | import static org.mockito.Mockito.verifyNoMoreInteractions; 17 | 18 | @RunWith(MockitoJUnitRunner.class) 19 | public class CommandQueueMockitoTest { 20 | 21 | private CommandQueue SUT; 22 | @Mock 23 | private CommandQueue.Receiver receiverMock; 24 | @Mock 25 | private CommandQueue.Receiver newReceiverMock; 26 | 27 | @Before 28 | public void setUp() throws Exception { 29 | SUT = new CommandQueue<>(); 30 | SUT.setReceiver(receiverMock); 31 | } 32 | 33 | @Test 34 | public void eventSentIsPassedToReceiver() { 35 | ArgumentCaptor ac = ArgumentCaptor.forClass(Integer.class); 36 | SUT.sendEvent(5); 37 | verify(receiverMock, times(1)).receiveCommand(ac.capture()); 38 | Assert.assertThat(ac.getValue(), is(5)); 39 | } 40 | 41 | @Test 42 | public void eventSentWhilePausedReceiverNotCalled() { 43 | SUT.setPaused(true); 44 | SUT.sendEvent(5); 45 | verifyNoMoreInteractions(receiverMock); 46 | } 47 | 48 | @Test 49 | public void eventsAreStoredWhileQueueIsPausedThenEmittedAfterQueueResumed() { 50 | ArgumentCaptor ac = ArgumentCaptor.forClass(Integer.class); 51 | SUT.setPaused(true); 52 | SUT.sendEvent(5); 53 | SUT.setPaused(false); 54 | verify(receiverMock, times(1)).receiveCommand(ac.capture()); 55 | Assert.assertThat(ac.getValue(), is(5)); 56 | } 57 | 58 | @Test 59 | public void multipleEventsSentAreReceiverInOrder() { 60 | ArgumentCaptor ac = ArgumentCaptor.forClass(Integer.class); 61 | SUT.sendEvent(5); 62 | SUT.sendEvent(6); 63 | SUT.sendEvent(7); 64 | verify(receiverMock, times(3)).receiveCommand(ac.capture()); 65 | List eventList = ac.getAllValues(); 66 | Assert.assertThat(eventList.get(0), is(5)); 67 | Assert.assertThat(eventList.get(1), is(6)); 68 | Assert.assertThat(eventList.get(2), is(7)); 69 | } 70 | 71 | @Test 72 | public void receiverNoLongerReceivesEventAfterDetaching() { 73 | SUT.detachReceiver(); 74 | SUT.sendEvent(5); 75 | verifyNoMoreInteractions(receiverMock); 76 | } 77 | 78 | @Test 79 | public void eventsAreStoredWhileNoReceiverExistsThenEmittedAfterReceiverRegistration() { 80 | ArgumentCaptor ac = ArgumentCaptor.forClass(Integer.class); 81 | SUT.detachReceiver(); 82 | SUT.sendEvent(5); 83 | SUT.setReceiver(receiverMock); 84 | verify(receiverMock, times(1)).receiveCommand(ac.capture()); 85 | Assert.assertThat(ac.getValue(), is(5)); 86 | } 87 | 88 | @Test 89 | public void settingANewReceiverMakesSureToOnlyReceiveNewEventThere() { 90 | ArgumentCaptor ac = ArgumentCaptor.forClass(Integer.class); 91 | SUT.setReceiver(newReceiverMock); 92 | SUT.sendEvent(5); 93 | verifyNoMoreInteractions(receiverMock); 94 | verify(newReceiverMock, times(1)).receiveCommand(ac.capture()); 95 | Assert.assertThat(ac.getValue(), is(5)); 96 | } 97 | } 98 | -------------------------------------------------------------------------------- /src/test/java/com/zhuinden/commandqueue/CommandQueueTest.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2018 Gabor Varadi 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package com.zhuinden.commandqueue; 17 | 18 | import org.junit.Assert; 19 | import org.junit.Test; 20 | 21 | import java.util.ArrayList; 22 | import java.util.List; 23 | import java.util.concurrent.CountDownLatch; 24 | import java.util.concurrent.TimeUnit; 25 | import java.util.concurrent.atomic.AtomicReference; 26 | 27 | import javax.annotation.Nonnull; 28 | 29 | import static org.assertj.core.api.Assertions.assertThat; 30 | 31 | public class CommandQueueTest { 32 | public abstract static class Events { 33 | public static class First extends Events { 34 | } 35 | 36 | public static class Second extends Events { 37 | } 38 | 39 | public static class Third extends Events { 40 | } 41 | 42 | public static class Fourth extends Events { 43 | } 44 | 45 | @Override 46 | public boolean equals(Object obj) { 47 | return obj != null && obj.getClass() == getClass(); 48 | } 49 | } 50 | 51 | @Test 52 | public void commandQueueWorks() { 53 | class Holder { 54 | T item; 55 | 56 | public Holder(T initial) { 57 | this.item = initial; 58 | } 59 | } 60 | 61 | final Holder firsts = new Holder<>(0); 62 | final Holder seconds = new Holder<>(0); 63 | 64 | CommandQueue queue = new CommandQueue<>(); 65 | 66 | CommandQueue.Receiver receiver = new CommandQueue.Receiver() { 67 | @Override 68 | public void receiveCommand(@Nonnull Events command) { 69 | if(command instanceof Events.First) { 70 | firsts.item += 1; 71 | } else if(command instanceof Events.Second) { 72 | seconds.item += 1; 73 | } 74 | } 75 | }; 76 | 77 | queue.setReceiver(receiver); 78 | 79 | assertThat(firsts.item).isEqualTo(0); 80 | assertThat(seconds.item).isEqualTo(0); 81 | 82 | queue.sendEvent(new Events.First()); 83 | 84 | assertThat(firsts.item).isEqualTo(1); 85 | assertThat(seconds.item).isEqualTo(0); 86 | 87 | queue.sendEvent(new Events.Second()); 88 | 89 | assertThat(firsts.item).isEqualTo(1); 90 | assertThat(seconds.item).isEqualTo(1); 91 | 92 | queue.detachReceiver(); 93 | 94 | queue.sendEvent(new Events.First()); 95 | queue.sendEvent(new Events.Second()); 96 | queue.sendEvent(new Events.Second()); 97 | queue.sendEvent(new Events.Second()); 98 | 99 | assertThat(firsts.item).isEqualTo(1); 100 | assertThat(seconds.item).isEqualTo(1); 101 | 102 | queue.setReceiver(receiver); 103 | 104 | assertThat(firsts.item).isEqualTo(2); 105 | assertThat(seconds.item).isEqualTo(4); 106 | } 107 | 108 | @Test 109 | public void nullEventIsDisallowed() { 110 | CommandQueue queue = new CommandQueue<>(); 111 | 112 | try { 113 | queue.sendEvent(null); 114 | Assert.fail(); 115 | } catch(IllegalArgumentException e) { 116 | // OK! 117 | } 118 | } 119 | 120 | @Test 121 | public void emittingEventsInReceiverPreservesOrder() { 122 | final CommandQueue queue = new CommandQueue<>(); 123 | 124 | final List eventsList = new ArrayList<>(); 125 | 126 | CommandQueue.Receiver receiver = new CommandQueue.Receiver() { 127 | @Override 128 | public void receiveCommand(@Nonnull Events command) { 129 | eventsList.add(command); 130 | if(command instanceof Events.First) { 131 | queue.detachReceiver(); 132 | queue.sendEvent(new Events.Second()); 133 | queue.sendEvent(new Events.Third()); 134 | queue.sendEvent(new Events.Second()); 135 | queue.sendEvent(new Events.Third()); 136 | queue.sendEvent(new Events.Second()); 137 | } else if(command instanceof Events.Second) { 138 | queue.sendEvent(new Events.Third()); 139 | } 140 | } 141 | }; 142 | 143 | queue.sendEvent(new Events.Fourth()); 144 | assertThat(eventsList).isEmpty(); 145 | 146 | queue.setReceiver(receiver); 147 | assertThat(eventsList).containsExactly(new Events.Fourth()); 148 | 149 | queue.sendEvent(new Events.First()); 150 | assertThat(eventsList).containsExactly(new Events.Fourth(), new Events.First()); 151 | 152 | queue.sendEvent(new Events.Fourth()); 153 | assertThat(eventsList).containsExactly(new Events.Fourth(), new Events.First()); 154 | 155 | queue.setReceiver(receiver); 156 | assertThat(eventsList).containsExactly(new Events.Fourth(), new Events.First(), new Events.Second(), new Events.Third(), new Events.Second(), new Events.Third(), new Events.Second(), new Events.Fourth(), new Events.Third(), new Events.Third(), new Events.Third()); 157 | } 158 | 159 | @Test 160 | public void hasReceiverWorksCorrectly() { 161 | final CommandQueue