feat: add negative compare-and-delete to imemcache

Signed-off-by: Robin Appelman <[email protected]>

lib/private/Memcache/CADTrait.php

@@ -35,4 +35,21 @@ public function cad($key, $old) {
  return false;
  }
  }
+
+ public function ncad(string $key, mixed $old): bool {
+ //no native cad, emulate with locking
+ if ($this->add($key . '_lock', true)) {
+ $value = $this->get($key);
+ if ($value !== null && $value !== $old) {
+ $this->remove($key);
+ $this->remove($key . '_lock');
+ return true;
+ } else {
+ $this->remove($key . '_lock');
+ return false;
+ }
+ } else {
+ return false;
+ }
+ }
 }

lib/private/Memcache/LoggerWrapperCache.php

@@ -149,6 +149,17 @@ public function cad($key, $old) {
  return $this->wrappedCache->cad($key, $old);
  }
 
+ /** @inheritDoc */
+ public function ncad(string $key, mixed $old): bool {
+ file_put_contents(
+ $this->logFile,
+ $this->getNameSpace() . '::ncad::' . $key . "\n",
+ FILE_APPEND
+ );
+
+ return $this->wrappedCache->cad($key, $old);
+ }
+
  /** @inheritDoc */
  public function setTTL(string $key, int $ttl) {
  $this->wrappedCache->setTTL($key, $ttl);

lib/private/Memcache/NullCache.php

@@ -43,6 +43,11 @@ public function cad($key, $old) {
  return true;
  }
 
+ public function ncad(string $key, mixed $old): bool {
+ return true;
+ }
+
+
  public function clear($prefix = '') {
  return true;
  }

lib/private/Memcache/ProfilerWrapperCache.php

@@ -166,6 +166,18 @@ public function cad($key, $old) {
  return $ret;
  }
 
+ /** @inheritDoc */
+ public function ncad(string $key, mixed $old): bool {
+ $start = microtime(true);
+ $ret = $this->wrappedCache->ncad($key, $old);
+ $this->data['queries'][] = [
+ 'start' => $start,
+ 'end' => microtime(true),
+ 'op' => $this->getPrefix() . '::ncad::' . $key,
+ ];
+ return $ret;
+ }
+
  /** @inheritDoc */
  public function setTTL(string $key, int $ttl) {
  $this->wrappedCache->setTTL($key, $ttl);

lib/private/Memcache/Redis.php

@@ -23,6 +23,10 @@ class Redis extends Cache implements IMemcacheTTL {
  'if redis.call("get", KEYS[1]) == ARGV[1] then return redis.call("del", KEYS[1]) else return 0 end',
  'cf0e94b2e9ffc7e04395cf88f7583fc309985910',
  ],
+ 'ncad' => [
+ 'if redis.call("get", KEYS[1]) ~= ARGV[1] then return redis.call("del", KEYS[1]) else return 0 end',
+ '75526f8048b13ce94a41b58eee59c664b4990ab2',
+ ],
  'caSetTtl' => [
  'if redis.call("get", KEYS[1]) == ARGV[1] then redis.call("expire", KEYS[1], ARGV[2]) return 1 else return 0 end',
  'fa4acbc946d23ef41d7d3910880b60e6e4972d72',
@@ -164,6 +168,12 @@ public function cad($key, $old) {
  return $this->evalLua('cad', [$key], [$old]) > 0;
  }
 
+ public function ncad(string $key, mixed $old): bool {
+ $old = self::encodeValue($old);
+
+ return $this->evalLua('ncad', [$key], [$old]) > 0;
+ }
+
  public function setTTL($key, $ttl) {
  if ($ttl === 0) {
  // having infinite TTL can lead to leaked keys as the prefix changes with version upgrades

lib/public/IMemcache.php

@@ -56,21 +56,37 @@ public function dec($key, $step = 1);
  /**
  * Compare and set
  *
+ * Set $key to $new only if it's current value is $new
+ *
  * @param string $key
  * @param mixed $old
  * @param mixed $new
- * @return bool
+ * @return bool true if the value was successfully set or false if $key wasn't set to $old
  * @since 8.1.0
  */
  public function cas($key, $old, $new);
 
  /**
  * Compare and delete
  *
+ * Delete $key if the stored value is equal to $old
+ *
  * @param string $key
  * @param mixed $old
- * @return bool
+ * @return bool true if the value was successfully deleted or false if $key wasn't set to $old
  * @since 8.1.0
  */
  public function cad($key, $old);
+
+ /**
+ * Negative compare and delete
+ *
+ * Delete $key if the stored value is not equal to $old
+ *
+ * @param string $key
+ * @param mixed $old
+ * @return bool true if the value was successfully deleted or false if $key was set to $old or is not set
+ * @since 30.0.0
+ */
+ public function ncad(string $key, mixed $old): bool;
 }

tests/lib/Memcache/Cache.php

@@ -109,6 +109,10 @@ public function testCasChanged() {
  $this->assertEquals('bar1', $this->instance->get('foo'));
  }
 
+ public function testCasNotSet() {
+ $this->assertFalse($this->instance->cas('foo', 'bar', 'asd'));
+ }
+
  public function testCadNotChanged() {
  $this->instance->set('foo', 'bar');
  $this->assertTrue($this->instance->cad('foo', 'bar'));
@@ -121,6 +125,25 @@ public function testCadChanged() {
  $this->assertTrue($this->instance->hasKey('foo'));
  }
 
+ public function testCadNotSet() {
+ $this->assertFalse($this->instance->cad('foo', 'bar'));
+ }
+
+ public function testNcadNotChanged() {
+ $this->instance->set('foo', 'bar');
+ $this->assertFalse($this->instance->ncad('foo', 'bar'));
+ $this->assertTrue($this->instance->hasKey('foo'));
+ }
+
+ public function testNcadChanged() {
+ $this->instance->set('foo', 'bar1');
+ $this->assertTrue($this->instance->ncad('foo', 'bar'));
+ $this->assertFalse($this->instance->hasKey('foo'));
+ }
+
+ public function testNcadNotSet() {
+ $this->assertFalse($this->instance->ncad('foo', 'bar'));
+ }
 
  protected function tearDown(): void {
  if ($this->instance) {