Locks.exists()

Author: Yegor Bugayenko

src/main/java/co/stateful/Locks.java

@@ -42,6 +42,15 @@
 @Immutable
 public interface Locks {
 
+    /**
+     * Does it exist?
+     * @param name Name of lock
+     * @return TRUE if the lock exists
+     * @throws IOException If fails
+     * @since 0.10
+     */
+    boolean exists(String name) throws IOException;
+
     /**
      * Get one lock by name.
      * @param name Name of lock

src/main/java/co/stateful/RtLocks.java

@@ -70,6 +70,18 @@ final class RtLocks implements Locks {
             .as(XmlResponse.class);
     }
 
+    @Override
+    public boolean exists(final String name) throws IOException {
+        return !this.response
+            .rel("/page/links/link[@rel='self']/@href")
+            .method(Request.GET)
+            .fetch()
+            .as(XmlResponse.class)
+            .xml()
+            .nodes(String.format("/page/locks/lock[name='%s']", name))
+            .isEmpty();
+    }
+
     @Override
     public Lock get(final String name) {
         return new RtLock(

src/main/java/co/stateful/RtSttc.java

@@ -38,6 +38,7 @@
 import com.jcabi.http.response.XmlResponse;
 import com.jcabi.http.wire.OneMinuteWire;
 import com.jcabi.http.wire.RetryWire;
+import com.jcabi.http.wire.VerboseWire;
 import com.jcabi.urn.URN;
 import java.io.IOException;
 import java.net.HttpURLConnection;
@@ -81,6 +82,7 @@ public RtSttc(final URN urn, final String token) {
         this.request = new JdkRequest("http://www.stateful.co")
             .through(OneMinuteWire.class)
             .through(RetryWire.class)
+            .through(VerboseWire.class)
             .header("X-Sttc-URN", urn.toString())
             .header("X-Sttc-Token", token)
             .header(HttpHeaders.ACCEPT, MediaType.TEXT_XML)

src/main/java/co/stateful/cached/CdLocks.java

@@ -65,6 +65,11 @@ public CdLocks(final Locks orgn) {
         this.origin = orgn;
     }
 
+    @Override
+    public boolean exists(final String name) throws IOException {
+        return this.origin.exists(name);
+    }
+
     @Override
     @Cacheable(lifetime = 1, unit = TimeUnit.HOURS)
     public Lock get(final String name) throws IOException {

src/main/java/co/stateful/mock/MkLocks.java

@@ -49,6 +49,11 @@
 @EqualsAndHashCode
 final class MkLocks implements Locks {
 
+    @Override
+    public boolean exists(final String name) {
+        return false;
+    }
+
     @Override
     public Lock get(final String name) {
         return new MkLock();

src/main/java/co/stateful/retry/ReLocks.java

@@ -66,6 +66,15 @@ public ReLocks(final Locks orgn) {
         this.origin = orgn;
     }
 
+    @Override
+    @RetryOnFailure(
+        verbose = false, attempts = Tv.TWENTY,
+        delay = Tv.FIVE, unit = TimeUnit.SECONDS
+    )
+    public boolean exists(final String name) throws IOException {
+        return this.origin.exists(name);
+    }
+
     @Override
     @RetryOnFailure(
         verbose = false, attempts = Tv.TWENTY,

src/test/java/co/stateful/RtLocksITCase.java

@@ -109,4 +109,27 @@ public Void call() throws Exception {
         );
     }
 
+    /**
+     * RtLocks can manage locks in one simple thread.
+     * @throws Exception If some problem inside
+     */
+    @Test
+    public void locksAndUnlocksInOneThread() throws Exception {
+        final Sttc sttc = this.srule.get();
+        final Locks locks = sttc.locks();
+        final String name = String.format(
+            "test2-%s", RtLocksITCase.RANDOM.nextInt(Integer.MAX_VALUE)
+        );
+        MatcherAssert.assertThat(locks.exists(name), Matchers.is(false));
+        final Lock lock = locks.get(name);
+        lock.lock();
+        try {
+            MatcherAssert.assertThat(locks.exists(name), Matchers.is(true));
+            lock.unlock();
+            MatcherAssert.assertThat(locks.exists(name), Matchers.is(false));
+        } finally {
+            lock.unlock();
+        }
+    }
+
 }