initial commit

Author: ayedo

.gitignore

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+# Created by .ignore support plugin (hsz.mobi)
+### Kotlin template
+# Compiled class file
+*.class
+
+# Log file
+*.log
+
+# BlueJ files
+*.ctxt
+
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.nar
+*.ear
+*.zip
+*.tar.gz
+*.rar
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+
+### Gradle template
+.gradle
+/build/
+
+# Ignore Gradle GUI config
+gradle-app.setting
+
+# Avoid ignoring Gradle wrapper jar file (.jar files are usually ignored)
+!gradle-wrapper.jar
+
+# Cache of project
+.gradletasknamecache
+
+# # Work around https://youtrack.jetbrains.com/issue/IDEA-116898
+# gradle/wrapper/gradle-wrapper.properties
+
+.idea

README.md

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+# Postgres Notify Flowable
+
+Consume Postgres LISTEN/NOTIFY messages in your JVM applications using RxJava, and the standard Postgres JDBC driver.
+
+- Enables RxJava's rich API for asynchronous processing
+- Requires only a single database connection for as many subscribers as you want
+- Uses standard Postgres JDBC driver
+- Minimizes polling overhead by centralizing it
+
+## About
+
+The Postgres JDBC driver has built in support for retrieving LISTEN/NOTIFY messages. The provided API is functional and basic. This code is an adapter from this basic API to RxJava to allow for a much richer asynchronous API.
+
+Further, Postgres requires a dedicated connection to call LISTEN on. One has to be careful not to be too wasteful with database connections.  This code enables you to ergonomically share a single such connection for multiple usages in your application by making use of the reactive extensions `share()` functionality.
+
+The idea is that you create a single `PostgresNotifyFlowable`, providing it all channels you would like to LISTEN on, and then you can subscribe to this `Flowable` as many times as you want sharing a single database connection across your application.
+
+The standard Postgres JDBC driver API is built around polling to retrieve LISTEN/NOTIFY messages. This might be wasteful in some scenarios, but at the same time one might not want to forgo the advantages of using the standard driver over a non-standard non-polling based one. This code helps you minimize the overhead by making it simple to have centralized polling over a single connection.
+
+## How to Use
+
+```
+  val channels = PostgresNotifyFlowable.forChannels(
+        jdbcUrl = db.jdbcUrl,
+        user = db.username,
+        password = db.password,
+        channels = listOf("hello"))
+  
+   channels
+        .filter({ it.name == "test" })
+        .subscribe({ notification: PGNotification ->
+           
+        })
+```

build.gradle

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+plugins {
+    id 'org.jetbrains.kotlin.jvm' version '1.3.50'
+}
+
+group 'ayedo'
+version '1.0.0'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
+    implementation 'org.slf4j:slf4j-api:1.7.25'
+    implementation 'org.postgresql:postgresql:42.2.8'
+    implementation 'io.reactivex.rxjava2:rxjava:2.2.13'
+    implementation 'io.reactivex.rxjava2:rxkotlin:2.4.0'
+
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.4.2'
+    testImplementation 'org.assertj:assertj-core:3.12.2'
+    testImplementation 'org.testcontainers:testcontainers:1.12.3'
+    testImplementation "org.testcontainers:junit-jupiter:1.12.3"
+    testImplementation "org.testcontainers:postgresql:1.12.3"
+
+    testRuntime 'org.junit.jupiter:junit-jupiter-engine:5.4.2'
+    testRuntime 'org.slf4j:slf4j-simple:1.7.25'
+}
+
+test {
+    useJUnitPlatform()
+}
+
+compileKotlin {
+    kotlinOptions.jvmTarget = "1.8"
+}
+compileTestKotlin {
+    kotlinOptions.jvmTarget = "1.8"
+}

gradle.properties

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+kotlin.code.style=official

gradle/wrapper/gradle-wrapper.jar

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+#Sat Nov 02 10:31:30 CET 2019
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.2.1-all.zip
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStorePath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME

gradle/wrapper/gradle-wrapper.properties

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+rootProject.name = 'notifyflowable'
+