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..712ab9d
--- /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..b83499c
--- /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..8306744
--- /dev/null
+++ b/.idea/vcs.xml
@@ -0,0 +1,7 @@
+
+
+
+
+
+
+
\ 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..f76857a 100644
--- a/src/main/java/dev/banking/model/BankAccount.java
+++ b/src/main/java/dev/banking/model/BankAccount.java
@@ -1,10 +1,14 @@
package dev.banking.model;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.concurrent.locks.Condition;
public class BankAccount {
private final int accountId;
private long balance;
-
+ private final ReentrantLock lock = new ReentrantLock();
+ private final Condition sufficientFunds = lock.newCondition();
/*
* Students may introduce additional fields
* such as:
@@ -31,8 +35,16 @@ public class BankAccount {
* - Must be safe under concurrent reads/writes
* - Should not block unnecessarily if using read/write locks
*/
- public long getBalance() {
- throw new UnsupportedOperationException("TODO: implement thread-safe balance read");
+ public long getBalance()
+ {
+ lock.lock();
+ try{
+ return this.balance ;
+ }finally {
+ lock.unlock();
+ }
+
+
}
/*
@@ -42,8 +54,16 @@ public class BankAccount {
* Requirements:
* - Must not lose updates under concurrency
*/
+
public void deposit(long amount) {
- throw new UnsupportedOperationException("TODO: implement thread-safe deposit");
+ if (amount <= 0) return;
+ lock.lock();
+ try {
+ this.balance += amount ;
+
+ }finally {
+ lock.unlock();
+ }
}
/*
@@ -56,7 +76,21 @@ public class BankAccount {
* to extend the system (optional)
*/
public void withdraw(long amount) {
- throw new UnsupportedOperationException("TODO: implement thread-safe withdraw");
+
+ lock.lock();
+ try {
+ while (this.balance < amount )
+ {
+ try {
+ sufficientFunds.await();
+ } catch (InterruptedException e) {
+ throw new RuntimeException(e);
+ }
+ }
+ this.balance -= amount ;
+ }finally {
+ lock.unlock();
+ }
}
/*
@@ -73,6 +107,30 @@ public class BankAccount {
* - Or tryLock with retry strategy
*/
public void transfer(BankAccount target, long amount) {
- throw new UnsupportedOperationException("TODO: implement atomic deadlock-free transfer");
+ if (target == null || amount <= 0 || target.accountId == this.accountId ) return;
+ BankAccount firstAccount ;
+ BankAccount secondAccount ;
+ if (this.accountId < target.accountId )
+ {
+ firstAccount = this ;
+ secondAccount = target ;
+ }
+ else {
+ firstAccount = target ;
+ secondAccount = this ;
+ }
+ firstAccount.lock.lock();
+ try {
+ secondAccount.lock.lock();
+ try {
+ this.balance -= amount ;
+ target.balance += amount ;
+ }finally {
+ secondAccount.lock.unlock();
+ }
+ }finally {
+ firstAccount.lock.unlock();
+ }
+
}
}
\ No newline at end of file