From ca59d7e5ea59597b4c980fb6b209dd53d560bed9 Mon Sep 17 00:00:00 2001 From: Bita Date: Fri, 12 Jun 2026 00:51:34 +0330 Subject: [PATCH] Complete the project --- .idea/.gitignore | 10 ++++ .idea/compiler.xml | 13 +++++ .idea/encodings.xml | 7 +++ .idea/jarRepositories.xml | 20 +++++++ .idea/misc.xml | 12 +++++ .idea/vcs.xml | 6 +++ .../java/dev/banking/model/BankAccount.java | 52 +++++++++++++++++-- 7 files changed, 116 insertions(+), 4 deletions(-) create mode 100644 .idea/.gitignore create mode 100644 .idea/compiler.xml create mode 100644 .idea/encodings.xml create mode 100644 .idea/jarRepositories.xml create mode 100644 .idea/misc.xml create mode 100644 .idea/vcs.xml 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..9cdf507 100644 --- a/src/main/java/dev/banking/model/BankAccount.java +++ b/src/main/java/dev/banking/model/BankAccount.java @@ -1,10 +1,16 @@ package dev.banking.model; +import java.util.concurrent.locks.ReentrantLock; +import java.util.concurrent.locks.ReentrantReadWriteLock; + public class BankAccount { private final int accountId; private long balance; + private final ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock(); + private final ReentrantLock transferLock = new ReentrantLock(); + /* * Students may introduce additional fields * such as: @@ -32,7 +38,12 @@ public class BankAccount { * - Should not block unnecessarily if using read/write locks */ public long getBalance() { - throw new UnsupportedOperationException("TODO: implement thread-safe balance read"); + rwLock.readLock().lock(); + try { + return balance; + } finally { + rwLock.readLock().unlock(); + } } /* @@ -43,7 +54,12 @@ public class BankAccount { * - Must not lose updates under concurrency */ public void deposit(long amount) { - throw new UnsupportedOperationException("TODO: implement thread-safe deposit"); + rwLock.writeLock().lock(); + try { + balance += amount; + } finally { + rwLock.writeLock().unlock(); + } } /* @@ -56,7 +72,12 @@ public class BankAccount { * to extend the system (optional) */ public void withdraw(long amount) { - throw new UnsupportedOperationException("TODO: implement thread-safe withdraw"); + rwLock.writeLock().lock(); + try { + balance -= amount; + } finally { + rwLock.writeLock().unlock(); + } } /* @@ -73,6 +94,29 @@ 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 first; + BankAccount second; + + if (this.getAccountId() < target.getAccountId()) { + first = this; + second = target; + } else { + first = target; + second = this; + } + + first.transferLock.lock(); + + try { + second.transferLock.lock(); + try { + first.balance -= amount; + target.balance += amount; + } finally { + second.transferLock.unlock(); + } + } finally { + first.transferLock.unlock(); + } } } \ No newline at end of file