diff options
Diffstat (limited to 'impl_core/src/main/java/io/opencensus/implcore/trace/propagation/BinaryFormatImpl.java')
| -rw-r--r-- | impl_core/src/main/java/io/opencensus/implcore/trace/propagation/BinaryFormatImpl.java | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/impl_core/src/main/java/io/opencensus/implcore/trace/propagation/BinaryFormatImpl.java b/impl_core/src/main/java/io/opencensus/implcore/trace/propagation/BinaryFormatImpl.java new file mode 100644 index 00000000..233fbd31 --- /dev/null +++ b/impl_core/src/main/java/io/opencensus/implcore/trace/propagation/BinaryFormatImpl.java @@ -0,0 +1,148 @@ +/* + * Copyright 2017, 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.trace.propagation; + +import static com.google.common.base.Preconditions.checkNotNull; + +import com.google.common.annotations.VisibleForTesting; +import io.opencensus.trace.SpanContext; +import io.opencensus.trace.SpanId; +import io.opencensus.trace.TraceId; +import io.opencensus.trace.TraceOptions; +import io.opencensus.trace.Tracestate; +import io.opencensus.trace.propagation.BinaryFormat; +import io.opencensus.trace.propagation.SpanContextParseException; + +/** + * Implementation of the {@link BinaryFormat}. + * + * <p>BinaryFormat format: + * + * <ul> + * <li>Binary value: <version_id><version_format> + * <li>version_id: 1-byte representing the version id. + * <li>For version_id = 0: + * <ul> + * <li>version_format: <field><field> + * <li>field_format: <field_id><field_format> + * <li>Fields: + * <ul> + * <li>TraceId: (field_id = 0, len = 16, default = "0000000000000000") - + * 16-byte array representing the trace_id. + * <li>SpanId: (field_id = 1, len = 8, default = "00000000") - 8-byte array + * representing the span_id. + * <li>TraceOptions: (field_id = 2, len = 1, default = "0") - 1-byte array + * representing the trace_options. + * </ul> + * <li>Fields MUST be encoded using the field id order (smaller to higher). + * <li>Valid value example: + * <ul> + * <li>{0, 0, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 1, 97, + * 98, 99, 100, 101, 102, 103, 104, 2, 1} + * <li>version_id = 0; + * <li>trace_id = {64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79} + * <li>span_id = {97, 98, 99, 100, 101, 102, 103, 104}; + * <li>trace_options = {1}; + * </ul> + * </ul> + * </ul> + */ +final class BinaryFormatImpl extends BinaryFormat { + private static final Tracestate TRACESTATE_DEFAULT = Tracestate.builder().build(); + private static final byte VERSION_ID = 0; + private static final int VERSION_ID_OFFSET = 0; + // The version_id/field_id size in bytes. + private static final byte ID_SIZE = 1; + private static final byte TRACE_ID_FIELD_ID = 0; + + // TODO: clarify if offsets are correct here. While the specification suggests you should stop + // parsing when you hit an unknown field, it does not suggest that fields must be declared in + // ID order. Rather it only groups by data type order, in this case Trace Context + // https://github.com/census-instrumentation/opencensus-specs/blob/master/encodings/BinaryEncoding.md#deserialization-rules + @VisibleForTesting static final int TRACE_ID_FIELD_ID_OFFSET = VERSION_ID_OFFSET + ID_SIZE; + + private static final int TRACE_ID_OFFSET = TRACE_ID_FIELD_ID_OFFSET + ID_SIZE; + private static final byte SPAN_ID_FIELD_ID = 1; + + @VisibleForTesting static final int SPAN_ID_FIELD_ID_OFFSET = TRACE_ID_OFFSET + TraceId.SIZE; + + private static final int SPAN_ID_OFFSET = SPAN_ID_FIELD_ID_OFFSET + ID_SIZE; + private static final byte TRACE_OPTION_FIELD_ID = 2; + + @VisibleForTesting static final int TRACE_OPTION_FIELD_ID_OFFSET = SPAN_ID_OFFSET + SpanId.SIZE; + + private static final int TRACE_OPTIONS_OFFSET = TRACE_OPTION_FIELD_ID_OFFSET + ID_SIZE; + /** Version, Trace and Span IDs are required fields. */ + private static final int REQUIRED_FORMAT_LENGTH = 3 * ID_SIZE + TraceId.SIZE + SpanId.SIZE; + /** Use {@link TraceOptions#DEFAULT} unless its optional field is present. */ + private static final int ALL_FORMAT_LENGTH = REQUIRED_FORMAT_LENGTH + ID_SIZE + TraceOptions.SIZE; + + @Override + public byte[] toByteArray(SpanContext spanContext) { + checkNotNull(spanContext, "spanContext"); + byte[] bytes = new byte[ALL_FORMAT_LENGTH]; + bytes[VERSION_ID_OFFSET] = VERSION_ID; + bytes[TRACE_ID_FIELD_ID_OFFSET] = TRACE_ID_FIELD_ID; + spanContext.getTraceId().copyBytesTo(bytes, TRACE_ID_OFFSET); + bytes[SPAN_ID_FIELD_ID_OFFSET] = SPAN_ID_FIELD_ID; + spanContext.getSpanId().copyBytesTo(bytes, SPAN_ID_OFFSET); + bytes[TRACE_OPTION_FIELD_ID_OFFSET] = TRACE_OPTION_FIELD_ID; + spanContext.getTraceOptions().copyBytesTo(bytes, TRACE_OPTIONS_OFFSET); + return bytes; + } + + @Override + public SpanContext fromByteArray(byte[] bytes) throws SpanContextParseException { + checkNotNull(bytes, "bytes"); + if (bytes.length == 0 || bytes[0] != VERSION_ID) { + throw new SpanContextParseException("Unsupported version."); + } + if (bytes.length < REQUIRED_FORMAT_LENGTH) { + throw new SpanContextParseException("Invalid input: truncated"); + } + // TODO: the following logic assumes that fields are written in ID order. The spec does not say + // that. If it decides not to, this logic would need to be more like a loop + TraceId traceId; + SpanId spanId; + TraceOptions traceOptions = TraceOptions.DEFAULT; + int pos = 1; + if (bytes[pos] == TRACE_ID_FIELD_ID) { + traceId = TraceId.fromBytes(bytes, pos + ID_SIZE); + pos += ID_SIZE + TraceId.SIZE; + } else { + // TODO: update the spec to suggest that the trace ID is not actually optional + throw new SpanContextParseException("Invalid input: expected trace ID at offset " + pos); + } + if (bytes[pos] == SPAN_ID_FIELD_ID) { + spanId = SpanId.fromBytes(bytes, pos + ID_SIZE); + pos += ID_SIZE + SpanId.SIZE; + } else { + // TODO: update the spec to suggest that the span ID is not actually optional. + throw new SpanContextParseException("Invalid input: expected span ID at offset " + pos); + } + // Check to see if we are long enough to include an options field, and also that the next field + // is an options field. Per spec we simply stop parsing at first unknown field instead of + // failing. + if (bytes.length > pos && bytes[pos] == TRACE_OPTION_FIELD_ID) { + if (bytes.length < ALL_FORMAT_LENGTH) { + throw new SpanContextParseException("Invalid input: truncated"); + } + traceOptions = TraceOptions.fromByte(bytes[pos + ID_SIZE]); + } + return SpanContext.create(traceId, spanId, traceOptions, TRACESTATE_DEFAULT); + } +} |