Bound registry work in progress

Signed-off-by: Bogdan Cristian Drutu <bogdandrutu@gmail.com>

sdk/src/main/java/io/opentelemetry/sdk/metrics/AbstractBoundInstrument.java

@@ -17,6 +17,7 @@
 package io.opentelemetry.sdk.metrics;
 
 import io.opentelemetry.metrics.InstrumentWithBinding.BoundInstrument;
+import io.opentelemetry.metrics.LabelSet;
 import io.opentelemetry.sdk.metrics.aggregator.Aggregator;
 import java.util.concurrent.atomic.AtomicLong;
 
@@ -32,11 +33,13 @@ abstract class AbstractBoundInstrument implements BoundInstrument {
   // Atomically counts the number of references (usages) while also keeping a state of
   // mapped/unmapped into a registry map.
   private final AtomicLong refCountMapped;
+  private final ActiveViewAggregator activeViewAggregator;
   private final Aggregator aggregator;
 
-  AbstractBoundInstrument(Aggregator aggregator) {
-    this.aggregator = aggregator;
+  AbstractBoundInstrument(ActiveViewAggregator activeViewAggregator) {
     this.refCountMapped = new AtomicLong(0);
+    this.activeViewAggregator = activeViewAggregator;
+    this.aggregator = activeViewAggregator.newAggregator();
   }
 
   /**
@@ -78,4 +81,8 @@ final void recordLong(long value) {
   final void recordDouble(double value) {
     aggregator.recordDouble(value);
   }
+
+  final void collect(LabelSet labelSet) {
+    activeViewAggregator.collect(labelSet, aggregator);
+  }
 }

sdk/src/main/java/io/opentelemetry/sdk/metrics/AbstractInstrument.java

@@ -32,6 +32,7 @@ abstract class AbstractInstrument implements Instrument {
   private final List<String> labelKeys;
   private final MeterSharedState meterSharedState;
   private final InstrumentationLibraryInfo instrumentationLibraryInfo;
+  private final ActiveViewAggregator activeViewAggregator;
 
   // All arguments cannot be null because they are checked in the abstract builder classes.
   AbstractInstrument(
@@ -51,6 +52,12 @@ abstract class AbstractInstrument implements Instrument {
     this.labelKeys = labelKeys;
     this.meterSharedState = meterSharedState;
     this.instrumentationLibraryInfo = instrumentationLibraryInfo;
+    activeViewAggregator =
+        new ActiveViewAggregator(
+            instrumentType,
+            instrumentValueType,
+            meterSharedState.getResource(),
+            instrumentationLibraryInfo);
   }
 
   final String getName() {
@@ -81,6 +88,10 @@ final InstrumentationLibraryInfo getInstrumentationLibraryInfo() {
     return instrumentationLibraryInfo;
   }
 
+  final ActiveViewAggregator getActiveViewAggregator() {
+    return activeViewAggregator;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {

sdk/src/main/java/io/opentelemetry/sdk/metrics/AbstractInstrumentWithBinding.java

@@ -0,0 +1,116 @@
+/*
+ * Copyright 2020, OpenTelemetry Authors
+ *
+ * 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.opentelemetry.sdk.metrics;
+
+import io.opentelemetry.metrics.LabelSet;
+import io.opentelemetry.sdk.common.InstrumentationLibraryInfo;
+import io.opentelemetry.sdk.metrics.common.InstrumentType;
+import io.opentelemetry.sdk.metrics.common.InstrumentValueType;
+import io.opentelemetry.sdk.metrics.data.MetricData;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.ReentrantLock;
+
+abstract class AbstractInstrumentWithBinding<B extends AbstractBoundInstrument>
+    extends AbstractInstrument {
+  private final ConcurrentHashMap<LabelSet, B> boundLabels;
+  private final ReentrantLock collectLock;
+  private long collectionStartTime;
+
+  AbstractInstrumentWithBinding(
+      String name,
+      String description,
+      String unit,
+      Map<String, String> constantLabels,
+      List<String> labelKeys,
+      InstrumentType instrumentType,
+      InstrumentValueType instrumentValueType,
+      MeterSharedState meterSharedState,
+      InstrumentationLibraryInfo instrumentationLibraryInfo) {
+    super(
+        name,
+        description,
+        unit,
+        constantLabels,
+        labelKeys,
+        instrumentType,
+        instrumentValueType,
+        meterSharedState,
+        instrumentationLibraryInfo);
+    boundLabels = new ConcurrentHashMap<>();
+    collectLock = new ReentrantLock();
+    collectionStartTime = getMeterSharedState().getClock().now();
+  }
+
+  // Cannot make this "bind" because of a Java problem if we make this class also implement the
+  // InstrumentWithBinding then the subclass will fail to compile because of different "bind"
+  // signature. This is a good trade-off.
+  final B bindInternal(LabelSet labelSet) {
+    B binding = boundLabels.get(labelSet);
+    if (binding != null && binding.bind()) {
+      // At this moment it is guaranteed that the Bound is in the map and will not be removed.
+      return binding;
+    }
+
+    // Missing entry or no longer mapped, try to add a new entry.
+    binding = newBinding();
+    while (true) {
+      B oldBound = boundLabels.putIfAbsent(labelSet, binding);
+      if (oldBound != null) {
+        if (oldBound.bind()) {
+          // At this moment it is guaranteed that the Bound is in the map and will not be removed.
+          return oldBound;
+        }
+        // Try to remove the oldBound. This will race with the collect method, but only one will
+        // succeed.
+        boundLabels.remove(labelSet, oldBound);
+        continue;
+      }
+      return binding;
+    }
+  }
+
+  /**
+   * Collects records from all the entries (labelSet, Bound) that changed since the last collect()
+   * call.
+   */
+  final Collection<MetricData> collect() {
+    getActiveViewAggregator().startCollection();
+    long previousCollectionStartTime = collectionStartTime;
+    collectionStartTime = getMeterSharedState().getClock().now();
+    collectLock.lock();
+    try {
+      for (Map.Entry<LabelSet, B> entry : boundLabels.entrySet()) {
+        if (entry.getValue().tryUnmap()) {
+          // If able to unmap then remove the record from the current Map. This can race with the
+          // acquire but because we requested a specific value only one will succeed.
+          boundLabels.remove(entry.getKey(), entry.getValue());
+        }
+
+        entry.getValue().collect(entry.getKey());
+      }
+    } finally {
+      collectLock.unlock();
+    }
+    return getActiveViewAggregator()
+        .stopCollection(previousCollectionStartTime, collectionStartTime);
+  }
+
+  abstract B newBinding();
+}

sdk/src/main/java/io/opentelemetry/sdk/metrics/ActiveViewAggregator.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2020, OpenTelemetry Authors
+ *
+ * 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.opentelemetry.sdk.metrics;
+
+import io.opentelemetry.metrics.LabelSet;
+import io.opentelemetry.sdk.common.InstrumentationLibraryInfo;
+import io.opentelemetry.sdk.metrics.aggregator.Aggregator;
+import io.opentelemetry.sdk.metrics.common.InstrumentType;
+import io.opentelemetry.sdk.metrics.common.InstrumentValueType;
+import io.opentelemetry.sdk.metrics.data.MetricData;
+import io.opentelemetry.sdk.metrics.data.MetricData.Descriptor;
+import io.opentelemetry.sdk.metrics.view.Aggregation;
+import io.opentelemetry.sdk.resources.Resource;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Map;
+import javax.annotation.Nullable;
+
+// The current implementation allows to change the active ViewAggregator only before any record
+// or binding happens. This is good for the moment to support default aggregation for all the
+// instruments but needs to support adding/removing views at any moment, as well as support for
+// multiple views in the same time.
+final class ActiveViewAggregator {
+  private final InstrumentType instrumentType;
+  private final InstrumentValueType instrumentValueType;
+  private final Resource resource;
+  private final InstrumentationLibraryInfo instrumentationLibraryInfo;
+  private AggregatorMap aggregatorMap;
+  private volatile AggregatorView currentAggregatorView;
+
+  ActiveViewAggregator(
+      InstrumentType instrumentType,
+      InstrumentValueType instrumentValueType,
+      Resource resource,
+      InstrumentationLibraryInfo instrumentationLibraryInfo) {
+    this.instrumentType = instrumentType;
+    this.instrumentValueType = instrumentValueType;
+    this.resource = resource;
+    this.instrumentationLibraryInfo = instrumentationLibraryInfo;
+    currentAggregatorView = AggregatorView.getNoop();
+  }
+
+  // TODO: Change this to: void addViewAggregator(View view);
+  void addView(
+      String name,
+      String description,
+      String unit,
+      Map<String, String> constantLabels,
+      Aggregation aggregation) {
+    // TODO: Add support to reduce labels.
+    this.currentAggregatorView =
+        AggregatorView.getAllLabels(
+            toDescriptor(
+                name,
+                description,
+                unit,
+                constantLabels,
+                aggregation,
+                instrumentType,
+                instrumentValueType),
+            resource,
+            instrumentationLibraryInfo,
+            aggregation.getAggregatorFactory(instrumentValueType));
+  }
+
+  // Caller needs to call these methods in the following order (while holding a lock):
+  //  * startCollection();
+  //  * collect();  // May be called multiple times.
+  //  * startCollection()
+  void startCollection() {
+    aggregatorMap = currentAggregatorView.newAggregatorMap();
+  }
+
+  void collect(LabelSet labelSet, Aggregator aggregator) {
+    aggregatorMap.collect(labelSet, aggregator);
+  }
+
+  Collection<MetricData> stopCollection(long startEpochNanos, long epochNanos) {
+    @Nullable MetricData metricData = aggregatorMap.toMetricData(startEpochNanos, epochNanos);
+    return metricData == null
+        ? Collections.<MetricData>emptyList()
+        : Collections.singletonList(metricData);
+  }
+
+  Aggregator newAggregator() {
+    return currentAggregatorView.getAggregator();
+  }
+
+  // This should change the signature when we add View to be:
+  // static Descriptor toDescriptor(View, InstrumentType, InstrumentValueType);
+  private static Descriptor toDescriptor(
+      String name,
+      String description,
+      String unit,
+      Map<String, String> constantLabels,
+      Aggregation aggregation,
+      InstrumentType instrumentType,
+      InstrumentValueType instrumentValueType) {
+    return Descriptor.create(
+        name,
+        description,
+        unit,
+        aggregation.getDescriptorType(instrumentType, instrumentValueType),
+        constantLabels);
+  }
+}