context: add basic context profiling

context/src/main/java/io/grpc/Context.java

@@ -17,13 +17,16 @@
 package io.grpc;
 
 import java.io.Closeable;
+import java.lang.reflect.Method;
 import java.util.ArrayList;
+import java.util.Random;
 import java.util.concurrent.Callable;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicLongArray;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -100,6 +103,55 @@ public class Context {
   private static final PersistentHashArrayMappedTrie<Key<?>, Object> EMPTY_ENTRIES =
       new PersistentHashArrayMappedTrie<Key<?>, Object>();
 
+  static final AtomicLongArray withValueCounts;
+  /**
+   * Counts how many times a unique value added to the context.
+   */
+  static final AtomicLongArray withValueUniqueCounts;
+  static final AtomicLongArray getCounts;
+  private static final Method threadLocalRandomCurrent;
+
+  static {
+    Method localThreadLocalRandomCurrent = null;
+    try {
+      Class<?> cls = Class.forName("java.util.concurrent.ThreadLocalRandom");
+      localThreadLocalRandomCurrent = cls.getMethod("current");
+      // call it once just to check.
+      localThreadLocalRandomCurrent.invoke(null);
+    } catch (Throwable t) {
+      log.log(Level.FINE, "Can't find TLR, skipping", t);
+      localThreadLocalRandomCurrent = null;
+    }
+    if (localThreadLocalRandomCurrent != null) {
+      withValueCounts = new AtomicLongArray(100);
+      withValueUniqueCounts = new AtomicLongArray(100);
+      getCounts = new AtomicLongArray(100);
+      threadLocalRandomCurrent = localThreadLocalRandomCurrent;
+    } else {
+      withValueCounts = new AtomicLongArray(0);
+      withValueUniqueCounts = new AtomicLongArray(0);
+      getCounts = new AtomicLongArray(0);
+      threadLocalRandomCurrent = null;
+    }
+  }
+
+  private static boolean shouldSample() {
+    if (threadLocalRandomCurrent == null) {
+      return false;
+    }
+    Random r;
+    try {
+      r = (Random) threadLocalRandomCurrent.invoke(null);
+    } catch (Exception e) {
+      log.log(Level.FINE, "Can't get TLR", e);
+      return false;
+    }
+    if (r.nextInt(256) != 0) {
+      return false;
+    }
+    return true;
+  }
+
   // Long chains of contexts are suspicious and usually indicate a misuse of Context.
   // The threshold is arbitrarily chosen.
   // VisibleForTesting
@@ -316,7 +368,15 @@ public class Context {
    *
    */
   public <V> Context withValue(Key<V> k1, V v1) {
-    return new Context(this, keyValueEntries.put(k1, v1));
+    PersistentHashArrayMappedTrie<Key<?>, Object> newKeyValueEntries = keyValueEntries.put(k1, v1);
+    if (shouldSample()) {
+      withValueUniqueCounts.addAndGet(
+          Math.min(keyValueEntries.size(), withValueUniqueCounts.length() - 1),
+          newKeyValueEntries.size() - keyValueEntries.size());
+      withValueCounts.incrementAndGet(
+          Math.min(keyValueEntries.size(), withValueCounts.length() - 1));
+    }
+    return new Context(this, newKeyValueEntries);
   }
 
   /**
@@ -324,7 +384,17 @@ public class Context {
    * from its parent.
    */
   public <V1, V2> Context withValues(Key<V1> k1, V1 v1, Key<V2> k2, V2 v2) {
-    return new Context(this, keyValueEntries.put(k1, v1).put(k2, v2));
+    PersistentHashArrayMappedTrie<Key<?>, Object> newKeyValueEntries =
+        keyValueEntries.put(k1, v1).put(k2, v2);
+    if (shouldSample()) {
+      withValueUniqueCounts.addAndGet(
+          Math.min(keyValueEntries.size(), withValueUniqueCounts.length() - 1),
+          newKeyValueEntries.size() - keyValueEntries.size());
+      withValueCounts.addAndGet(
+          Math.min(keyValueEntries.size(), withValueCounts.length() - 1),
+          2);
+    }
+    return new Context(this, newKeyValueEntries);
   }
 
   /**
@@ -332,7 +402,17 @@ public class Context {
    * from its parent.
    */
   public <V1, V2, V3> Context withValues(Key<V1> k1, V1 v1, Key<V2> k2, V2 v2, Key<V3> k3, V3 v3) {
-    return new Context(this, keyValueEntries.put(k1, v1).put(k2, v2).put(k3, v3));
+    PersistentHashArrayMappedTrie<Key<?>, Object> newKeyValueEntries =
+        keyValueEntries.put(k1, v1).put(k2, v2).put(k3, v3);
+    if (shouldSample()) {
+      withValueUniqueCounts.addAndGet(
+          Math.min(keyValueEntries.size(), withValueUniqueCounts.length() - 1),
+          newKeyValueEntries.size() - keyValueEntries.size());
+      withValueCounts.addAndGet(
+          Math.min(keyValueEntries.size(), withValueCounts.length() - 1),
+          3);
+    }
+    return new Context(this, newKeyValueEntries);
   }
 
   /**
@@ -341,7 +421,17 @@ public class Context {
    */
   public <V1, V2, V3, V4> Context withValues(Key<V1> k1, V1 v1, Key<V2> k2, V2 v2,
       Key<V3> k3, V3 v3, Key<V4> k4, V4 v4) {
-    return new Context(this, keyValueEntries.put(k1, v1).put(k2, v2).put(k3, v3).put(k4, v4));
+    PersistentHashArrayMappedTrie<Key<?>, Object> newKeyValueEntries =
+        keyValueEntries.put(k1, v1).put(k2, v2).put(k3, v3).put(k4, v4);
+    if (shouldSample()) {
+      withValueUniqueCounts.addAndGet(
+          Math.min(keyValueEntries.size(), withValueUniqueCounts.length() - 1),
+          newKeyValueEntries.size() - keyValueEntries.size());
+      withValueCounts.addAndGet(
+          Math.min(keyValueEntries.size(), withValueCounts.length() - 1),
+          4);
+    }
+    return new Context(this, newKeyValueEntries);
   }
 
   /**
@@ -650,6 +740,9 @@ public class Context {
    * Lookup the value for a key in the context inheritance chain.
    */
   private Object lookup(Key<?> key) {
+    if (shouldSample()) {
+      getCounts.incrementAndGet(Math.min(keyValueEntries.size(), getCounts.length() - 1));
+    }
     return keyValueEntries.get(key);
   }
 

context/src/main/java/io/grpc/InternalContext.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2018, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc;
+
+import java.util.concurrent.atomic.AtomicLongArray;
+
+/**
+ * Internal accessor for {@link InternalContext}.
+ */
+public final class InternalContext {
+  public static AtomicLongArray getCounts() {
+    return Context.getCounts;
+  }
+
+  public static AtomicLongArray withValueCounts() {
+    return Context.withValueCounts;
+  }
+
+  public static AtomicLongArray withValueUniqueCounts() {
+    return Context.withValueUniqueCounts;
+  }
+}

context/src/main/java/io/grpc/PersistentHashArrayMappedTrie.java

@@ -40,6 +40,13 @@ final class PersistentHashArrayMappedTrie<K,V> {
     this.root = root;
   }
 
+  public int size() {
+    if (root == null) {
+      return 0;
+    }
+    return root.size();
+  }
+
   /**
    * Returns the value with the specified key, or {@code null} if it does not exist.
    */
@@ -72,6 +79,11 @@ final class PersistentHashArrayMappedTrie<K,V> {
       this.value = value;
     }
 
+    @Override
+    public int size() {
+      return 1;
+    }
+
     @Override
     public V get(K key, int hash, int bitsConsumed) {
       if (this.key == key) {
@@ -124,6 +136,11 @@ final class PersistentHashArrayMappedTrie<K,V> {
       this.values = values;
     }
 
+    @Override
+    public int size() {
+      return values.length;
+    }
+
     @Override
     public V get(K key, int hash, int bitsConsumed) {
       for (int i = 0; i < keys.length; i++) {
@@ -188,10 +205,17 @@ final class PersistentHashArrayMappedTrie<K,V> {
 
     final int bitmap;
     final Node<K,V>[] values;
+    private final int size;
 
-    private CompressedIndex(int bitmap, Node<K,V>[] values) {
+    private CompressedIndex(int bitmap, Node<K,V>[] values, int size) {
       this.bitmap = bitmap;
       this.values = values;
+      this.size = size;
+    }
+
+    @Override
+    public int size() {
+      return size;
     }
 
     @Override
@@ -221,13 +245,16 @@ final class PersistentHashArrayMappedTrie<K,V> {
             newValues,
             compressedIndex + 1,
             values.length - compressedIndex);
-        return new CompressedIndex<K,V>(newBitmap, newValues);
+        return new CompressedIndex<K,V>(newBitmap, newValues, size() + 1);
       } else {
         // Replace
         Node<K,V>[] newValues = Arrays.copyOf(values, values.length);
         newValues[compressedIndex] =
             values[compressedIndex].put(key, value, hash, bitsConsumed + BITS);
-        return new CompressedIndex<K,V>(bitmap, newValues);
+        int newSize = size();
+        newSize += newValues[compressedIndex].size();
+        newSize -= values[compressedIndex].size();
+        return new CompressedIndex<K,V>(bitmap, newValues, newSize);
       }
     }
 
@@ -240,7 +267,7 @@ final class PersistentHashArrayMappedTrie<K,V> {
         Node<K,V> node = combine(node1, hash1, node2, hash2, bitsConsumed + BITS);
         @SuppressWarnings("unchecked")
         Node<K,V>[] values = (Node<K,V>[]) new Node<?,?>[] {node};
-        return new CompressedIndex<K,V>(indexBit1, values);
+        return new CompressedIndex<K,V>(indexBit1, values, node.size());
       } else {
         // Make node1 the smallest
         if (uncompressedIndex(hash1, bitsConsumed) > uncompressedIndex(hash2, bitsConsumed)) {
@@ -250,7 +277,7 @@ final class PersistentHashArrayMappedTrie<K,V> {
         }
         @SuppressWarnings("unchecked")
         Node<K,V>[] values = (Node<K,V>[]) new Node<?,?>[] {node1, node2};
-        return new CompressedIndex<K,V>(indexBit1 | indexBit2, values);
+        return new CompressedIndex<K,V>(indexBit1 | indexBit2, values, node1.size() + node2.size());
       }
     }
 
@@ -283,5 +310,7 @@ final class PersistentHashArrayMappedTrie<K,V> {
     V get(K key, int hash, int bitsConsumed);
 
     Node<K,V> put(K key, V value, int hash, int bitsConsumed);
+
+    int size();
   }
 }

context/src/test/java/io/grpc/PersistentHashArrayMappedTrieTest.java

@@ -41,6 +41,9 @@ public class PersistentHashArrayMappedTrieTest {
     assertSame(value2, ret.get(key, key.hashCode(), 0));
 
     assertSame(value1, leaf.get(key, key.hashCode(), 0));
+
+    assertEquals(1, leaf.size());
+    assertEquals(1, ret.size());
   }
 
   @Test
@@ -57,6 +60,9 @@ public class PersistentHashArrayMappedTrieTest {
 
     assertSame(value1, leaf.get(key1, key1.hashCode(), 0));
     assertSame(null, leaf.get(key2, key2.hashCode(), 0));
+
+    assertEquals(1, leaf.size());
+    assertEquals(2, ret.size());
   }
 
   @Test
@@ -73,6 +79,9 @@ public class PersistentHashArrayMappedTrieTest {
 
     assertSame(value1, leaf.get(key1, key1.hashCode(), 0));
     assertSame(null, leaf.get(key2, key2.hashCode(), 0));
+
+    assertEquals(1, leaf.size());
+    assertEquals(2, ret.size());
   }
 
   @Test(expected = AssertionError.class)
@@ -106,6 +115,9 @@ public class PersistentHashArrayMappedTrieTest {
     assertSame(value1, leaf.get(key1, key1.hashCode(), 0));
     assertSame(value2, leaf.get(key2, key2.hashCode(), 0));
     assertSame(null, leaf.get(insertKey, insertKey.hashCode(), 0));
+
+    assertEquals(2, leaf.size());
+    assertEquals(3, ret.size());
   }
 
   @Test
@@ -124,6 +136,9 @@ public class PersistentHashArrayMappedTrieTest {
 
     assertSame(value, leaf.get(key, key.hashCode(), 0));
     assertSame(originalValue, leaf.get(replaceKey, replaceKey.hashCode(), 0));
+
+    assertEquals(2, leaf.size());
+    assertEquals(2, ret.size());
   }
 
   @Test
@@ -146,6 +161,9 @@ public class PersistentHashArrayMappedTrieTest {
     assertSame(value1, leaf.get(key1, key1.hashCode(), 0));
     assertSame(value2, leaf.get(key2, key2.hashCode(), 0));
     assertSame(null, leaf.get(key3, key3.hashCode(), 0));
+
+    assertEquals(2, leaf.size());
+    assertEquals(3, ret.size());
   }
 
   @Test
@@ -166,12 +184,17 @@ public class PersistentHashArrayMappedTrieTest {
 
         assertSame(value1, ret.get(key1, key1.hashCode(), 0));
         assertSame(value2, ret.get(key2, key2.hashCode(), 0));
+
+        assertEquals(2, ret.size());
       }
     }
 
     Verifier verifier = new Verifier();
     verifier.verify(CompressedIndex.combine(leaf1, key1.hashCode(), leaf2, key2.hashCode(), 0));
     verifier.verify(CompressedIndex.combine(leaf2, key2.hashCode(), leaf1, key1.hashCode(), 0));
+
+    assertEquals(1, leaf1.size());
+    assertEquals(1, leaf2.size());
   }
 
   @Test
@@ -192,12 +215,17 @@ public class PersistentHashArrayMappedTrieTest {
         assertEquals((1 << 31) | (1 << 17), collisionLeaf.bitmap);
         assertSame(value1, ret.get(key1, key1.hashCode(), 0));
         assertSame(value2, ret.get(key2, key2.hashCode(), 0));
+
+        assertEquals(2, ret.size());
       }
     }
 
     Verifier verifier = new Verifier();
     verifier.verify(CompressedIndex.combine(leaf1, key1.hashCode(), leaf2, key2.hashCode, 0));
     verifier.verify(CompressedIndex.combine(leaf2, key2.hashCode(), leaf1, key1.hashCode, 0));
+
+    assertEquals(1, leaf1.size());
+    assertEquals(1, leaf2.size());
   }
 
   /**