Merge pull request #1225 from square/jwilson.0914.nextSourceHacks
Small improvements to JsonReader.nextSource
diff --git a/moshi/src/main/java/com/squareup/moshi/JsonUtf8Reader.java b/moshi/src/main/java/com/squareup/moshi/JsonUtf8Reader.java
index c0f7d2d..06b9652 100644
--- a/moshi/src/main/java/com/squareup/moshi/JsonUtf8Reader.java
+++ b/moshi/src/main/java/com/squareup/moshi/JsonUtf8Reader.java
@@ -241,10 +241,6 @@
}
private int doPeek() throws IOException {
- if (valueSource != null) {
- valueSource.discard();
- valueSource = null;
- }
int peekStack = scopes[stackSize - 1];
if (peekStack == JsonScope.EMPTY_ARRAY) {
scopes[stackSize - 1] = JsonScope.NONEMPTY_ARRAY;
@@ -329,6 +325,13 @@
} else {
checkLenient();
}
+ } else if (peekStack == JsonScope.STREAMING_VALUE) {
+ valueSource.discard();
+ valueSource = null;
+ stackSize--;
+ pathIndices[stackSize - 1]++;
+ pathNames[stackSize - 1] = "null";
+ return doPeek();
} else if (peekStack == JsonScope.CLOSED) {
throw new IllegalStateException("JsonReader is closed");
}
@@ -1067,9 +1070,8 @@
}
valueSource = new JsonValueSource(source, prefix, state, valueSourceStackSize);
+ pushScope(JsonScope.STREAMING_VALUE);
peeked = PEEKED_NONE;
- pathIndices[stackSize - 1]++;
- pathNames[stackSize - 1] = "null";
return Okio.buffer(valueSource);
}
diff --git a/moshi/src/main/java/com/squareup/moshi/JsonValueSource.java b/moshi/src/main/java/com/squareup/moshi/JsonValueSource.java
index 4bc895a..7f1f5ef 100644
--- a/moshi/src/main/java/com/squareup/moshi/JsonValueSource.java
+++ b/moshi/src/main/java/com/squareup/moshi/JsonValueSource.java
@@ -76,7 +76,14 @@
}
/**
- * Advance {@link #limit} until it is at least {@code byteCount} or the JSON object is complete.
+ * Advance {@link #limit} until any of these conditions are met:
+ *
+ * <ul>
+ * <li>Limit is at least {@code byteCount}. We can satisfy the caller's request!
+ * <li>The JSON value is complete. This stream is exhausted.
+ * <li>We have some data to return and returning more would require reloading the buffer. We
+ * prefer to return some data immediately when more data requires blocking.
+ * </ul>
*
* @throws EOFException if the stream is exhausted before the JSON object completes.
*/
@@ -87,9 +94,10 @@
return;
}
- // If advancing requires more data in the buffer, grow it.
+ // If we can't return any bytes without more data in the buffer, grow the buffer.
if (limit == buffer.size()) {
- source.require(limit + 1L);
+ if (limit > 0L) return;
+ source.require(1L);
}
// Find the next interesting character for the current state. If the buffer doesn't have one,
@@ -196,6 +204,7 @@
if (!prefix.exhausted()) {
long prefixResult = prefix.read(sink, byteCount);
byteCount -= prefixResult;
+ if (buffer.exhausted()) return prefixResult; // Defer a blocking call.
long suffixResult = read(sink, byteCount);
return suffixResult != -1L ? suffixResult + prefixResult : prefixResult;
}
diff --git a/moshi/src/test/java/com/squareup/moshi/JsonUtf8ReaderTest.java b/moshi/src/test/java/com/squareup/moshi/JsonUtf8ReaderTest.java
index 2b04d4e..6317445 100644
--- a/moshi/src/test/java/com/squareup/moshi/JsonUtf8ReaderTest.java
+++ b/moshi/src/test/java/com/squareup/moshi/JsonUtf8ReaderTest.java
@@ -38,6 +38,7 @@
import okio.BufferedSource;
import okio.ForwardingSource;
import okio.Okio;
+import okio.Source;
import org.junit.Ignore;
import org.junit.Test;
@@ -1408,4 +1409,81 @@
assertThat(valueSource.readUtf8()).isEqualTo("-2");
}
}
+
+ /**
+ * Confirm that {@link JsonReader#nextSource} doesn't load data from the underlying stream until
+ * its required by the caller. If the source is backed by a slow network stream, we want users to
+ * get data as it arrives.
+ *
+ * <p>Because we don't have a slow stream in this test, we just add bytes to our underlying stream
+ * immediately before they're needed.
+ */
+ @Test
+ public void nextSourceStreams() throws IOException {
+ Buffer stream = new Buffer();
+ stream.writeUtf8("[\"");
+
+ JsonReader reader = JsonReader.of(Okio.buffer((Source) stream));
+ reader.beginArray();
+ BufferedSource source = reader.nextSource();
+ assertThat(source.readUtf8(1)).isEqualTo("\"");
+ stream.writeUtf8("hello");
+ assertThat(source.readUtf8(5)).isEqualTo("hello");
+ stream.writeUtf8("world");
+ assertThat(source.readUtf8(5)).isEqualTo("world");
+ stream.writeUtf8("\"");
+ assertThat(source.readUtf8(1)).isEqualTo("\"");
+ stream.writeUtf8("]");
+ assertThat(source.exhausted()).isTrue();
+ reader.endArray();
+ }
+
+ @Test
+ public void nextSourceObjectAfterSelect() throws IOException {
+ // language=JSON
+ JsonReader reader = newReader("[\"p\u0065psi\"]");
+ reader.beginArray();
+ assertThat(reader.selectName(JsonReader.Options.of("coke"))).isEqualTo(-1);
+ try (BufferedSource valueSource = reader.nextSource()) {
+ assertThat(valueSource.readUtf8()).isEqualTo("\"pepsi\""); // not the original characters!
+ }
+ }
+
+ @Test
+ public void nextSourceObjectAfterPromoteNameToValue() throws IOException {
+ // language=JSON
+ JsonReader reader = newReader("{\"a\":true}");
+ reader.beginObject();
+ reader.promoteNameToValue();
+ try (BufferedSource valueSource = reader.nextSource()) {
+ assertThat(valueSource.readUtf8()).isEqualTo("\"a\"");
+ }
+ assertThat(reader.nextBoolean()).isEqualTo(true);
+ reader.endObject();
+ }
+
+ @Test
+ public void nextSourcePath() throws IOException {
+ // language=JSON
+ JsonReader reader = newReader("{\"a\":true,\"b\":[],\"c\":false}");
+ reader.beginObject();
+
+ assertThat(reader.nextName()).isEqualTo("a");
+ assertThat(reader.getPath()).isEqualTo("$.a");
+ assertThat(reader.nextBoolean()).isTrue();
+ assertThat(reader.getPath()).isEqualTo("$.a");
+
+ assertThat(reader.nextName()).isEqualTo("b");
+ try (BufferedSource valueSource = reader.nextSource()) {
+ assertThat(reader.getPath()).isEqualTo("$.b");
+ assertThat(valueSource.readUtf8()).isEqualTo("[]");
+ }
+ assertThat(reader.getPath()).isEqualTo("$.b");
+
+ assertThat(reader.nextName()).isEqualTo("c");
+ assertThat(reader.getPath()).isEqualTo("$.c");
+ assertThat(reader.nextBoolean()).isFalse();
+ assertThat(reader.getPath()).isEqualTo("$.c");
+ reader.endObject();
+ }
}
