1 files changed, 138 insertions, 0 deletions
diff --git a/impl_core/src/main/java/io/opencensus/implcore/stats/MeasureMapInternal.java b/impl_core/src/main/java/io/opencensus/implcore/stats/MeasureMapInternal.java
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+++ b/impl_core/src/main/java/io/opencensus/implcore/stats/MeasureMapInternal.java
@@ -0,0 +1,138 @@
+/*
+ * Copyright 2016-17, OpenCensus 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.opencensus.implcore.stats;
+
+import io.opencensus.stats.Measure;
+import io.opencensus.stats.Measure.MeasureDouble;
+import io.opencensus.stats.Measure.MeasureLong;
+import io.opencensus.stats.Measurement;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.NoSuchElementException;
+
+// TODO(songya): consider combining MeasureMapImpl and this class.
+/** A map from {@link Measure}'s to measured values. */
+final class MeasureMapInternal {
+
+  /** Returns a {@link Builder} for the {@link MeasureMapInternal} class. */
+  static Builder builder() {
+    return new Builder();
+  }
+
+  /**
+   * Returns an {@link Iterator} over the measure/value mappings in this {@link MeasureMapInternal}.
+   * The {@code Iterator} does not support {@link Iterator#remove()}.
+   */
+  Iterator<Measurement> iterator() {
+    return new MeasureMapInternalIterator();
+  }
+
+  // Returns the contextual information associated with an example value.
+  Map<String, String> getAttachments() {
+    return attachments;
+  }
+
+  private final ArrayList<Measurement> measurements;
+  private final Map<String, String> attachments;
+
+  private MeasureMapInternal(ArrayList<Measurement> measurements, Map<String, String> attachments) {
+    this.measurements = measurements;
+    this.attachments = Collections.unmodifiableMap(new HashMap<String, String>(attachments));
+  }
+
+  /** Builder for the {@link MeasureMapInternal} class. */
+  static class Builder {
+    /**
+     * Associates the {@link MeasureDouble} with the given value. Subsequent updates to the same
+     * {@link MeasureDouble} will overwrite the previous value.
+     *
+     * @param measure the {@link MeasureDouble}
+     * @param value the value to be associated with {@code measure}
+     * @return this
+     */
+    Builder put(MeasureDouble measure, double value) {
+      measurements.add(Measurement.MeasurementDouble.create(measure, value));
+      return this;
+    }
+
+    /**
+     * Associates the {@link MeasureLong} with the given value. Subsequent updates to the same
+     * {@link MeasureLong} will overwrite the previous value.
+     *
+     * @param measure the {@link MeasureLong}
+     * @param value the value to be associated with {@code measure}
+     * @return this
+     */
+    Builder put(MeasureLong measure, long value) {
+      measurements.add(Measurement.MeasurementLong.create(measure, value));
+      return this;
+    }
+
+    Builder putAttachment(String key, String value) {
+      this.attachments.put(key, value);
+      return this;
+    }
+
+    /** Constructs a {@link MeasureMapInternal} from the current measurements. */
+    MeasureMapInternal build() {
+      // Note: this makes adding measurements quadratic but is fastest for the sizes of
+      // MeasureMapInternals that we should see. We may want to go to a strategy of sort/eliminate
+      // for larger MeasureMapInternals.
+      for (int i = measurements.size() - 1; i >= 0; i--) {
+        for (int j = i - 1; j >= 0; j--) {
+          if (measurements.get(i).getMeasure() == measurements.get(j).getMeasure()) {
+            measurements.remove(j);
+            j--;
+          }
+        }
+      }
+      return new MeasureMapInternal(measurements, attachments);
+    }
+
+    private final ArrayList<Measurement> measurements = new ArrayList<Measurement>();
+    private final Map<String, String> attachments = new HashMap<String, String>();
+
+    private Builder() {}
+  }
+
+  // Provides an unmodifiable Iterator over this instance's measurements.
+  private final class MeasureMapInternalIterator implements Iterator<Measurement> {
+    @Override
+    public boolean hasNext() {
+      return position < length;
+    }
+
+    @Override
+    public Measurement next() {
+      if (position >= measurements.size()) {
+        throw new NoSuchElementException();
+      }
+      return measurements.get(position++);
+    }
+
+    @Override
+    public void remove() {
+      throw new UnsupportedOperationException();
+    }
+
+    private final int length = measurements.size();
+    private int position = 0;
+  }
+}