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Diffstat (limited to 'vendor/go.opencensus.io/trace/propagation/propagation.go')
| -rw-r--r-- | vendor/go.opencensus.io/trace/propagation/propagation.go | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/vendor/go.opencensus.io/trace/propagation/propagation.go b/vendor/go.opencensus.io/trace/propagation/propagation.go new file mode 100644 index 0000000..1eb190a --- /dev/null +++ b/vendor/go.opencensus.io/trace/propagation/propagation.go @@ -0,0 +1,108 @@ +// 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 propagation implements the binary trace context format. +package propagation // import "go.opencensus.io/trace/propagation" + +// TODO: link to external spec document. + +// BinaryFormat format: +// +// Binary value: <version_id><version_format> +// version_id: 1 byte representing the version id. +// +// For version_id = 0: +// +// version_format: <field><field> +// field_format: <field_id><field_format> +// +// Fields: +// +// TraceId: (field_id = 0, len = 16, default = "0000000000000000") - 16-byte array representing the trace_id. +// SpanId: (field_id = 1, len = 8, default = "00000000") - 8-byte array representing the span_id. +// TraceOptions: (field_id = 2, len = 1, default = "0") - 1-byte array representing the trace_options. +// +// Fields MUST be encoded using the field id order (smaller to higher). +// +// Valid value example: +// +// {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} +// +// version_id = 0; +// trace_id = {64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79} +// span_id = {97, 98, 99, 100, 101, 102, 103, 104}; +// trace_options = {1}; + +import ( + "net/http" + + "go.opencensus.io/trace" +) + +// Binary returns the binary format representation of a SpanContext. +// +// If sc is the zero value, Binary returns nil. +func Binary(sc trace.SpanContext) []byte { + if sc == (trace.SpanContext{}) { + return nil + } + var b [29]byte + copy(b[2:18], sc.TraceID[:]) + b[18] = 1 + copy(b[19:27], sc.SpanID[:]) + b[27] = 2 + b[28] = uint8(sc.TraceOptions) + return b[:] +} + +// FromBinary returns the SpanContext represented by b. +// +// If b has an unsupported version ID or contains no TraceID, FromBinary +// returns with ok==false. +func FromBinary(b []byte) (sc trace.SpanContext, ok bool) { + if len(b) == 0 || b[0] != 0 { + return trace.SpanContext{}, false + } + b = b[1:] + if len(b) >= 17 && b[0] == 0 { + copy(sc.TraceID[:], b[1:17]) + b = b[17:] + } else { + return trace.SpanContext{}, false + } + if len(b) >= 9 && b[0] == 1 { + copy(sc.SpanID[:], b[1:9]) + b = b[9:] + } + if len(b) >= 2 && b[0] == 2 { + sc.TraceOptions = trace.TraceOptions(b[1]) + } + return sc, true +} + +// HTTPFormat implementations propagate span contexts +// in HTTP requests. +// +// SpanContextFromRequest extracts a span context from incoming +// requests. +// +// SpanContextToRequest modifies the given request to include the given +// span context. +type HTTPFormat interface { + SpanContextFromRequest(req *http.Request) (sc trace.SpanContext, ok bool) + SpanContextToRequest(sc trace.SpanContext, req *http.Request) +} + +// TODO(jbd): Find a more representative but short name for HTTPFormat. |