Only apply size limit to the bytes representing tag keys and values. (#807)

* Only apply size limit to the bytes representing tag keys and values.

* Reword error message when size exceeds limit

* Add a note about chars == bytes

3 files changed, 55 insertions, 31 deletions

diff --git a/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextDeserializationTest.java b/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextDeserializationTest.java
index f6d8dd09..273a6ce2 100644
--- a/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextDeserializationTest.java
+++ b/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextDeserializationTest.java
@@ -78,9 +78,30 @@ public class TagContextDeserializationTest {
   @Test
   public void testDeserializeTooLargeByteArrayThrowException()
       throws TagContextDeserializationException {
+    ByteArrayDataOutput output = ByteStreams.newDataOutput();
+    output.write(SerializationUtils.VERSION_ID);
+    for (int i = 0; i < SerializationUtils.TAGCONTEXT_SERIALIZED_SIZE_LIMIT / 8 - 1; i++) {
+      // Each tag will be with format {key : "0123", value : "0123"}, so the length of it is 8.
+      String str;
+      if (i < 10) {
+        str = "000" + i;
+      } else if (i < 100) {
+        str = "00" + i;
+      } else if (i < 1000) {
+        str = "0" + i;
+      } else {
+        str = String.valueOf(i);
+      }
+      encodeTagToOutput(str, str, output);
+    }
+    // The last tag will be of size 9, so the total size of the TagContext (8193) will be one byte
+    // more than limit.
+    encodeTagToOutput("last", "last1", output);
+
+    byte[] bytes = output.toByteArray();
     thrown.expect(TagContextDeserializationException.class);
-    thrown.expectMessage("Size of input byte[] exceeds the maximum serialized size ");
-    serializer.fromByteArray(new byte[SerializationUtils.TAGCONTEXT_SERIALIZED_SIZE_LIMIT + 1]);
+    thrown.expectMessage("Size of TagContext exceeds the maximum serialized size ");
+    serializer.fromByteArray(bytes);
   }
 
   @Test
diff --git a/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextRoundtripTest.java b/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextRoundtripTest.java
index c49e53a4..1b1aa042 100644
--- a/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextRoundtripTest.java
+++ b/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextRoundtripTest.java
@@ -59,23 +59,22 @@ public class TagContextRoundtripTest {
   @Test
   public void testRoundtrip_TagContextWithMaximumSize() throws Exception {
     TagContextBuilder builder = tagger.emptyBuilder();
-    int i = 0;
-
-    // This loop should fill in tags that have a total size of 8185
-    while (serializer.toByteArray(builder.build()).length
-        < SerializationUtils.TAGCONTEXT_SERIALIZED_SIZE_LIMIT - 8) {
-      TagKey key = TagKey.create("k" + i);
-      TagValue value = TagValue.create("v" + i);
-      builder.put(key, value);
-      i++;
+    for (int i = 0; i < SerializationUtils.TAGCONTEXT_SERIALIZED_SIZE_LIMIT / 8; i++) {
+      // Each tag will be with format {key : "0123", value : "0123"}, so the length of it is 8.
+      // Add 1024 tags, the total size should just be 8192.
+      String str;
+      if (i < 10) {
+        str = "000" + i;
+      } else if (i < 100) {
+        str = "00" + i;
+      } else if (i < 1000) {
+        str = "0" + i;
+      } else {
+        str = "" + i;
+      }
+      builder.put(TagKey.create(str), TagValue.create(str));
     }
-    // The last tag has size 7, after putting it, the size of TagContext should just meet the limit
-    builder.put(TagKey.create("last"), TagValue.create(""));
-
-    TagContext expected = builder.build();
-    assertThat(serializer.toByteArray(expected).length)
-        .isEqualTo(SerializationUtils.TAGCONTEXT_SERIALIZED_SIZE_LIMIT);
-    testRoundtripSerialization(expected);
+    testRoundtripSerialization(builder.build());
   }
 
   private void testRoundtripSerialization(TagContext expected) throws Exception {
diff --git a/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextSerializationTest.java b/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextSerializationTest.java
index 551b7ff8..771b2899 100644
--- a/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextSerializationTest.java
+++ b/impl_core/src/test/java/io/opencensus/implcore/tags/propagation/TagContextSerializationTest.java
@@ -91,23 +91,27 @@ public class TagContextSerializationTest {
   @Test
   public void testSerializeTooLargeTagContext() throws TagContextSerializationException {
     TagContextBuilder builder = tagger.emptyBuilder();
-    int i = 0;
-
-    // This loop should fill in tags that have a total size of 8185
-    while (serializer.toByteArray(builder.build()).length
-        < SerializationUtils.TAGCONTEXT_SERIALIZED_SIZE_LIMIT - 8) {
-      TagKey key = TagKey.create("k" + i);
-      TagValue value = TagValue.create("v" + i);
-      builder.put(key, value);
-      i++;
+    for (int i = 0; i < SerializationUtils.TAGCONTEXT_SERIALIZED_SIZE_LIMIT / 8 - 1; i++) {
+      // Each tag will be with format {key : "0123", value : "0123"}, so the length of it is 8.
+      String str;
+      if (i < 10) {
+        str = "000" + i;
+      } else if (i < 100) {
+        str = "00" + i;
+      } else if (i < 1000) {
+        str = "0" + i;
+      } else {
+        str = String.valueOf(i);
+      }
+      builder.put(TagKey.create(str), TagValue.create(str));
     }
-    // The last tag has size 8, after putting it, the size of TagContext (8193) should just exceed
-    // the limit
-    builder.put(TagKey.create("last"), TagValue.create("1"));
+    // The last tag will be of size 9, so the total size of the TagContext (8193) will be one byte
+    // more than limit.
+    builder.put(TagKey.create("last"), TagValue.create("last1"));
 
     TagContext tagContext = builder.build();
     thrown.expect(TagContextSerializationException.class);
-    thrown.expectMessage("Size of serialized TagContext exceeds the maximum serialized size ");
+    thrown.expectMessage("Size of TagContext exceeds the maximum serialized size ");
     serializer.toByteArray(tagContext);
   }