added expiration functionality

README.md

@@ -45,6 +45,14 @@ int main(int argc, char *argv[]) {
     qDebug() << "Value for 'key_a':" << cache->fetch("key_a");
     qDebug() << "Value for 'key_b':" << cache->fetch("key_b");
 
+    cache->store("key_c", "a special value", 1);
+
+    qDebug() << "Has 'key_c' before sleep? -" << (cache->has("key_c") ? "yes" : "no");
+
+    sleep(2);
+
+    qDebug() << "Has 'key_c' after sleep? -" << (cache->has("key_c") ? "yes" : "no");
+
     return 0;
 }
 ```

abstractadapter.hpp

@@ -14,6 +14,7 @@ namespace Bidstack {
 
         public:
             virtual bool store(QString key, QString data) =0;
+            virtual bool store(QString key, QString data, int ttl) =0;
             virtual bool has(QString key) =0;
             virtual bool remove(QString key) =0;
             virtual bool clear() =0;

devnulladapter.cpp

@@ -7,8 +7,13 @@ DevNullAdapter::DevNullAdapter(QObject *parent) : AbstractAdapter(parent) {
 }
 
 bool DevNullAdapter::store(QString key, QString data) {
+    return store(key, data, 0);
+}
+
+bool DevNullAdapter::store(QString key, QString data, int ttl) {
     Q_UNUSED(key);
     Q_UNUSED(data);
+    Q_UNUSED(ttl);
     return true;
 }
 

devnulladapter.hpp

@@ -16,6 +16,7 @@ namespace Bidstack {
 
         public:
             bool store(QString key, QString data);
+            bool store(QString key, QString data, int ttl);
             bool has(QString key);
             bool remove(QString key);
             bool clear();

sqliteadapter.cpp

@@ -1,5 +1,7 @@
 #include "sqliteadapter.hpp"
 
+#include <QDateTime>
+
 using namespace Bidstack::Cache;
 
 SqliteAdapter::SqliteAdapter(QString filename, QObject *parent) : AbstractAdapter(parent) {
@@ -19,7 +21,8 @@ bool SqliteAdapter::init(QString filename) {
     const QString sql =
         "CREATE TABLE IF NOT EXISTS cache ("
             "key CHAR(32) PRIMARY KEY NOT NULL,"
-            "data TEXT NOT NULL"
+            "data TEXT NOT NULL,"
+            "expires_at INTEGER"
         ")";
 
     QSqlQuery stmt(sql, m_connection);
@@ -29,12 +32,19 @@ bool SqliteAdapter::init(QString filename) {
 }
 
 bool SqliteAdapter::store(QString key, QString data) {
-    const QString sql = "INSERT OR REPLACE INTO cache (key, data) VALUES (:key, :data)";
+    return store(key, data, 0);
+}
+
+bool SqliteAdapter::store(QString key, QString data, int ttl) {
+    const QString sql =
+      "INSERT OR REPLACE INTO cache (key, data, expires_at) "
+      "VALUES (:key, :data, :expires_at)";
 
     QSqlQuery stmt(m_connection);
     stmt.prepare(sql);
     stmt.bindValue(":key", key);
     stmt.bindValue(":data", data);
+    stmt.bindValue(":expires_at", now() + ttl);
     stmt.exec();
 
     return !stmt.lastError().isValid();
@@ -66,15 +76,23 @@ bool SqliteAdapter::clear() {
 }
 
 QString SqliteAdapter::fetch(QString key) {
-    const QString sql = "SELECT data FROM cache WHERE key = :key";
+    const QString sql = "SELECT expires_at, data FROM cache WHERE key = :key";
 
     QSqlQuery stmt(m_connection);
     stmt.prepare(sql);
     stmt.bindValue(":key", key);
     stmt.exec();
 
     if (!stmt.lastError().isValid() && stmt.next()) {
-        return stmt.value(0).toString();
+        uint expires_at = stmt.value(0).toUInt();
+
+        if ((expires_at == 0) || (expires_at >= now())) {
+            return stmt.value(1).toString();
+        }
+
+        if (!remove(key)) {
+            throw "Could not expire key '" + key + "'";
+        }
     }
 
     return "";
@@ -83,3 +101,7 @@ QString SqliteAdapter::fetch(QString key) {
 QString SqliteAdapter::fetch(QString key, QString defaultValue) {
     return has(key) ? fetch(key) : defaultValue;
 }
+
+uint SqliteAdapter::now() {
+    return QDateTime::currentDateTime().toTime_t();
+}

sqliteadapter.hpp

@@ -20,6 +20,7 @@ namespace Bidstack {
 
         public:
             bool store(QString key, QString data);
+            bool store(QString key, QString data, int ttl);
             bool has(QString key);
             bool remove(QString key);
             bool clear();
@@ -28,6 +29,7 @@ namespace Bidstack {
 
         private:
             bool init(QString filename);
+            uint now();
 
         private:
             QSqlDatabase m_connection;