From ef64ba88ab124cc217c7d437da8ad3af4be8b583 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Tue, 5 Feb 2019 14:19:29 -0500
Subject: [PATCH] Add mutex example

---
 .idea/misc.xml      |  1 +
 .idea/rust.iml      |  5 +++++
 .idea/workspace.xml | 46 ++++++++++++++++++++++++++-------------------
 mutex/Cargo.toml    |  7 +++++++
 mutex/src/main.rs   | 40 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 80 insertions(+), 19 deletions(-)
 create mode 100644 mutex/Cargo.toml
 create mode 100644 mutex/src/main.rs

diff --git a/.idea/misc.xml b/.idea/misc.xml
index 1c9acf9..76830ba 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -29,6 +29,7 @@
     <cargoProject FILE="$PROJECT_DIR$/interior_mutability/Cargo.toml" />
     <cargoProject FILE="$PROJECT_DIR$/reference_cycles/Cargo.toml" />
     <cargoProject FILE="$PROJECT_DIR$/threads/Cargo.toml" />
+    <cargoProject FILE="$PROJECT_DIR$/mutex/Cargo.toml" />
   </component>
   <component name="ComposerJsonPluginSettings">
     <unboundedVersionInspectionSettings>
diff --git a/.idea/rust.iml b/.idea/rust.iml
index 971bd3a..0650e07 100644
--- a/.idea/rust.iml
+++ b/.idea/rust.iml
@@ -118,6 +118,10 @@
       <sourceFolder url="file://$MODULE_DIR$/threads/examples" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/threads/tests" isTestSource="true" />
       <sourceFolder url="file://$MODULE_DIR$/threads/benches" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/mutex/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/mutex/examples" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/mutex/tests" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/mutex/benches" isTestSource="true" />
       <excludeFolder url="file://$MODULE_DIR$/add/add-one/target" />
       <excludeFolder url="file://$MODULE_DIR$/add/adder/target" />
       <excludeFolder url="file://$MODULE_DIR$/adder/target" />
@@ -136,6 +140,7 @@
       <excludeFolder url="file://$MODULE_DIR$/minigrep/target" />
       <excludeFolder url="file://$MODULE_DIR$/minigrep_v2/target" />
       <excludeFolder url="file://$MODULE_DIR$/modules/target" />
+      <excludeFolder url="file://$MODULE_DIR$/mutex/target" />
       <excludeFolder url="file://$MODULE_DIR$/rectangles/target" />
       <excludeFolder url="file://$MODULE_DIR$/reference_counting/target" />
       <excludeFolder url="file://$MODULE_DIR$/reference_cycles/target" />
diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index bdb3b8d..1826468 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -15,10 +15,10 @@
   <component name="FileEditorManager">
     <leaf>
       <file pinned="false" current-in-tab="true">
-        <entry file="file://$PROJECT_DIR$/threads/src/main.rs">
+        <entry file="file://$PROJECT_DIR$/mutex/src/main.rs">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="864">
-              <caret line="54" column="9" lean-forward="true" selection-start-line="54" selection-start-column="9" selection-end-line="54" selection-end-column="9" />
+            <state>
+              <caret column="91" selection-start-column="91" selection-end-column="91" />
             </state>
           </provider>
         </entry>
@@ -96,6 +96,7 @@
         <option value="$PROJECT_DIR$/reference_counting/src/main.rs" />
         <option value="$PROJECT_DIR$/reference_cycles/src/main.rs" />
         <option value="$PROJECT_DIR$/threads/src/main.rs" />
+        <option value="$PROJECT_DIR$/mutex/src/main.rs" />
       </list>
     </option>
   </component>
@@ -129,12 +130,12 @@
             <path>
               <item name="rust" type="3d21c010:ScopeViewTreeModel$ProjectNode" />
               <item name="rust" type="2674bda8:ScopeViewTreeModel$GroupNode" />
-              <item name="threads" type="9f88c78c:ScopeViewTreeModel$FileNode" />
+              <item name="mutex" type="9f88c78c:ScopeViewTreeModel$FileNode" />
             </path>
             <path>
               <item name="rust" type="3d21c010:ScopeViewTreeModel$ProjectNode" />
               <item name="rust" type="2674bda8:ScopeViewTreeModel$GroupNode" />
-              <item name="threads" type="9f88c78c:ScopeViewTreeModel$FileNode" />
+              <item name="mutex" type="9f88c78c:ScopeViewTreeModel$FileNode" />
               <item name="src" type="9f88c78c:ScopeViewTreeModel$FileNode" />
             </path>
           </expand>
@@ -168,7 +169,7 @@
   </component>
   <component name="PropertiesComponent">
     <property name="JavaScriptWeakerCompletionTypeGuess" value="true" />
-    <property name="com.android.tools.idea.instantapp.provision.ProvisionBeforeRunTaskProvider.myTimeStamp" value="1549393270881" />
+    <property name="com.android.tools.idea.instantapp.provision.ProvisionBeforeRunTaskProvider.myTimeStamp" value="1549394084677" />
     <property name="javascript.nodejs.core.library.configured.version" value="7.1.0" />
     <property name="js.eslint.eslintPackage" value="$USER_HOME$/.yarn-config/global/node_modules/.bin/eslint" />
     <property name="js.eslint.nodeInterpreter" value="project" />
@@ -196,7 +197,7 @@
       </list>
     </option>
   </component>
-  <component name="RunManager" selected="Cargo Command.Run threads">
+  <component name="RunManager" selected="Cargo Command.Run mutex">
     <configuration name="&lt;template&gt;" type="TestNG" default="true" selected="false">
       <option name="MAIN_CLASS_NAME" />
       <option name="VM_PARAMETERS" value="-ea" />
@@ -215,6 +216,16 @@
         <option name="Make" enabled="true" />
       </method>
     </configuration>
+    <configuration name="Run mutex" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
+      <option name="channel" value="DEFAULT" />
+      <option name="command" value="run --package mutex --bin mutex" />
+      <option name="allFeatures" value="false" />
+      <option name="nocapture" value="false" />
+      <option name="backtrace" value="SHORT" />
+      <option name="workingDirectory" value="file://$PROJECT_DIR$/mutex" />
+      <envs />
+      <method v="2" />
+    </configuration>
     <configuration name="Run reference_counting" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
       <option name="channel" value="DEFAULT" />
       <option name="command" value="run --package reference_counting --bin reference_counting" />
@@ -255,16 +266,6 @@
       <envs />
       <method v="2" />
     </configuration>
-    <configuration name="Test tests::it_sends_an_over_75_percent_warning_message" type="CargoCommandRunConfiguration" factoryName="Cargo Command" temporary="true">
-      <option name="channel" value="DEFAULT" />
-      <option name="command" value="test --package interior_mutability --lib tests::it_sends_an_over_75_percent_warning_message -- --exact" />
-      <option name="allFeatures" value="false" />
-      <option name="nocapture" value="false" />
-      <option name="backtrace" value="SHORT" />
-      <option name="workingDirectory" value="file://$PROJECT_DIR$/interior_mutability" />
-      <envs />
-      <method v="2" />
-    </configuration>
     <configuration default="true" type="JUnit" factoryName="JUnit">
       <option name="TEST_OBJECT" value="class" />
       <option name="WORKING_DIRECTORY" value="$MODULE_DIR$" />
@@ -274,11 +275,11 @@
     </configuration>
     <recent_temporary>
       <list>
+        <item itemvalue="Cargo Command.Run mutex" />
         <item itemvalue="Cargo Command.Run threads" />
         <item itemvalue="Cargo Command.Run reference_cycles" />
         <item itemvalue="Cargo Command.Run reference_counting" />
         <item itemvalue="Cargo Command.Test lib::tests" />
-        <item itemvalue="Cargo Command.Test tests::it_sends_an_over_75_percent_warning_message" />
       </list>
     </recent_temporary>
   </component>
@@ -765,7 +766,14 @@
     <entry file="file://$PROJECT_DIR$/threads/src/main.rs">
       <provider selected="true" editor-type-id="text-editor">
         <state relative-caret-position="864">
-          <caret line="54" column="9" lean-forward="true" selection-start-line="54" selection-start-column="9" selection-end-line="54" selection-end-column="9" />
+          <caret line="54" column="9" selection-start-line="54" selection-start-column="9" selection-end-line="54" selection-end-column="9" />
+        </state>
+      </provider>
+    </entry>
+    <entry file="file://$PROJECT_DIR$/mutex/src/main.rs">
+      <provider selected="true" editor-type-id="text-editor">
+        <state>
+          <caret column="91" selection-start-column="91" selection-end-column="91" />
         </state>
       </provider>
     </entry>
diff --git a/mutex/Cargo.toml b/mutex/Cargo.toml
new file mode 100644
index 0000000..c6b3678
--- /dev/null
+++ b/mutex/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "mutex"
+version = "0.1.0"
+authors = ["Timothy Warren <twarren@nabancard.com>"]
+edition = "2018"
+
+[dependencies]
diff --git a/mutex/src/main.rs b/mutex/src/main.rs
new file mode 100644
index 0000000..399ba50
--- /dev/null
+++ b/mutex/src/main.rs
@@ -0,0 +1,40 @@
+use std::sync::{Arc, Mutex}; // Rc is not thread safe, but Arc is. (Atomic Reference Count)
+use std::thread;
+
+fn single_thread_example() {
+    let m = Mutex::new(5);
+
+    {
+        let mut num = m.lock().unwrap();
+        *num = 6;
+    } // Reference to mutex value goes out of scope, lock is released
+
+    println!("m = {:?}", m);
+}
+
+fn multi_thread_example() {
+    let counter = Arc::new(Mutex::new(0));
+    let mut handles = vec![];
+
+    for _ in 0..10 {
+        let counter = Arc::clone(&counter);
+        let handle = thread::spawn(move || {
+           let mut num = counter.lock().unwrap();
+
+            *num += 1;
+        });
+        handles.push(handle);
+    }
+
+    for handle in handles {
+        handle.join().unwrap();
+    }
+
+    println!("Result: {}", *counter.lock().unwrap());
+}
+
+fn main() {
+    single_thread_example();
+
+    multi_thread_example();
+}