diff --git a/.idea/.gitignore b/.idea/.gitignore
new file mode 100644
index 0000000..ab1f416
--- /dev/null
+++ b/.idea/.gitignore
@@ -0,0 +1,10 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Ignored default folder with query files
+/queries/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml
+# Editor-based HTTP Client requests
+/httpRequests/
diff --git a/.idea/compiler.xml b/.idea/compiler.xml
new file mode 100644
index 0000000..812c3f9
--- /dev/null
+++ b/.idea/compiler.xml
@@ -0,0 +1,13 @@
+
+
+
+
+
+
+
+
+
+
+
+
+
\ No newline at end of file
diff --git a/.idea/encodings.xml b/.idea/encodings.xml
new file mode 100644
index 0000000..aa00ffa
--- /dev/null
+++ b/.idea/encodings.xml
@@ -0,0 +1,7 @@
+
+
+
+
+
+
+
\ No newline at end of file
diff --git a/.idea/jarRepositories.xml b/.idea/jarRepositories.xml
new file mode 100644
index 0000000..4158879
--- /dev/null
+++ b/.idea/jarRepositories.xml
@@ -0,0 +1,20 @@
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
new file mode 100644
index 0000000..eba6e1f
--- /dev/null
+++ b/.idea/misc.xml
@@ -0,0 +1,12 @@
+
+
+
+
+
+
+
+
\ No newline at end of file
diff --git a/.idea/vcs.xml b/.idea/vcs.xml
new file mode 100644
index 0000000..35eb1dd
--- /dev/null
+++ b/.idea/vcs.xml
@@ -0,0 +1,6 @@
+
+
+
+
+
+
\ No newline at end of file
diff --git a/src/main/java/dev/banking/model/BankAccount.java b/src/main/java/dev/banking/model/BankAccount.java
index 745ede2..88be025 100644
--- a/src/main/java/dev/banking/model/BankAccount.java
+++ b/src/main/java/dev/banking/model/BankAccount.java
@@ -1,4 +1,5 @@
package dev.banking.model;
+import java.util.concurrent.locks.ReentrantLock;
public class BankAccount {
@@ -13,7 +14,7 @@ public class BankAccount {
* - Object monitor
* - etc.
*/
-
+ private final ReentrantLock lock = new ReentrantLock();
public BankAccount(int accountId, long initialBalance) {
this.accountId = accountId;
this.balance = initialBalance;
@@ -32,7 +33,13 @@ public class BankAccount {
* - Should not block unnecessarily if using read/write locks
*/
public long getBalance() {
- throw new UnsupportedOperationException("TODO: implement thread-safe balance read");
+ lock.lock();
+ try{
+ return balance;
+ }
+ finally{
+ lock.unlock();
+ }
}
/*
@@ -43,7 +50,13 @@ public class BankAccount {
* - Must not lose updates under concurrency
*/
public void deposit(long amount) {
- throw new UnsupportedOperationException("TODO: implement thread-safe deposit");
+ lock.lock();
+ try{
+ balance += amount;
+ }
+ finally {
+ lock.unlock();
+ }
}
/*
@@ -56,7 +69,13 @@ public class BankAccount {
* to extend the system (optional)
*/
public void withdraw(long amount) {
- throw new UnsupportedOperationException("TODO: implement thread-safe withdraw");
+ lock.lock();
+ try{
+ balance -= amount;
+ }
+ finally{
+ lock.unlock();
+ }
}
/*
@@ -73,6 +92,28 @@ public class BankAccount {
* - Or tryLock with retry strategy
*/
public void transfer(BankAccount target, long amount) {
- throw new UnsupportedOperationException("TODO: implement atomic deadlock-free transfer");
+ BankAccount lock1;
+ BankAccount lock2;
+
+ if (this.accountId < target.accountId){
+ lock1 = this;
+ lock2 = target;
+ }
+ else{
+ lock1 = target;
+ lock2 = this;
+ }
+
+ lock1.lock.lock();
+ lock2.lock.lock();
+
+ try {
+ this.balance -= amount;
+ target.balance += amount;
+ }
+ finally{
+ lock2.lock.unlock();
+ lock1.lock.unlock();
+ }
}
}
\ No newline at end of file
diff --git a/structure.txt b/structure.txt
new file mode 100644
index 0000000..7d31940
Binary files /dev/null and b/structure.txt differ