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Remove duplicate code for grpc encoding, and extra class. (grpc#22334)
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* Remove duplicate code for grpc encoding, and extra class.

Originally from grpc#18359 by @bogdandrutu.

* Autoformat.
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@g-easy
g-easy authored Apr 8, 2021
1 parent a63f188 commit 57859e3
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Showing 6 changed files with 21 additions and 189 deletions.
1 change: 1 addition & 0 deletions BUILD
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Original file line number Diff line number Diff line change
Expand Up @@ -2748,6 +2748,7 @@ grpc_cc_library(
"absl-time",
"opencensus-trace",
"opencensus-trace-context_util",
"opencensus-trace-propagation",
"opencensus-stats",
"opencensus-context",
],
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5 changes: 5 additions & 0 deletions bazel/grpc_deps.bzl
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Expand Up @@ -121,6 +121,11 @@ def grpc_deps():
actual = "@io_opencensus_cpp//opencensus/trace:context_util",
)

native.bind(
name = "opencensus-trace-propagation",
actual = "@io_opencensus_cpp//opencensus/trace:grpc_trace_bin",
)

native.bind(
name = "opencensus-stats",
actual = "@io_opencensus_cpp//opencensus/stats:stats",
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24 changes: 13 additions & 11 deletions src/cpp/ext/filters/census/context.cc
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Expand Up @@ -20,6 +20,7 @@

#include "opencensus/tags/context_util.h"
#include "opencensus/trace/context_util.h"
#include "opencensus/trace/propagation/grpc_trace_bin.h"
#include "src/cpp/ext/filters/census/context.h"

namespace grpc {
Expand All @@ -33,14 +34,11 @@ void GenerateServerContext(absl::string_view tracing, absl::string_view method,
// Destruct the current CensusContext to free the Span memory before
// overwriting it below.
context->~CensusContext();
GrpcTraceContext trace_ctxt;
if (TraceContextEncoding::Decode(tracing, &trace_ctxt) !=
TraceContextEncoding::kEncodeDecodeFailure) {
SpanContext parent_ctx = trace_ctxt.ToSpanContext();
if (parent_ctx.IsValid()) {
new (context) CensusContext(method, parent_ctx);
return;
}
SpanContext parent_ctx =
opencensus::trace::propagation::FromGrpcTraceBinHeader(tracing);
if (parent_ctx.IsValid()) {
new (context) CensusContext(method, parent_ctx);
return;
}
new (context) CensusContext(method, TagMap{});
}
Expand Down Expand Up @@ -71,9 +69,13 @@ void GenerateClientContext(absl::string_view method, CensusContext* ctxt,

size_t TraceContextSerialize(const ::opencensus::trace::SpanContext& context,
char* tracing_buf, size_t tracing_buf_size) {
GrpcTraceContext trace_ctxt(context);
return TraceContextEncoding::Encode(trace_ctxt, tracing_buf,
tracing_buf_size);
if (tracing_buf_size <
opencensus::trace::propagation::kGrpcTraceBinHeaderLen) {
return 0;
}
opencensus::trace::propagation::ToGrpcTraceBinHeader(
context, reinterpret_cast<uint8_t*>(tracing_buf));
return opencensus::trace::propagation::kGrpcTraceBinHeaderLen;
}

size_t StatsContextSerialize(size_t /*max_tags_len*/, grpc_slice* /*tags*/) {
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4 changes: 2 additions & 2 deletions src/cpp/ext/filters/census/context.h
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Expand Up @@ -75,8 +75,8 @@ class CensusContext {
::opencensus::tags::TagMap tags_;
};

// Serializes the outgoing trace context. Field IDs are 1 byte followed by
// field data. A 1 byte version ID is always encoded first.
// Serializes the outgoing trace context. tracing_buf must be
// opencensus::trace::propagation::kGrpcTraceBinHeaderLen bytes long.
size_t TraceContextSerialize(const ::opencensus::trace::SpanContext& context,
char* tracing_buf, size_t tracing_buf_size);

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7 changes: 0 additions & 7 deletions src/cpp/ext/filters/census/rpc_encoding.cc
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Expand Up @@ -22,13 +22,6 @@

namespace grpc {

constexpr size_t TraceContextEncoding::kGrpcTraceContextSize;
constexpr size_t TraceContextEncoding::kEncodeDecodeFailure;
constexpr size_t TraceContextEncoding::kVersionIdSize;
constexpr size_t TraceContextEncoding::kFieldIdSize;
constexpr size_t TraceContextEncoding::kVersionIdOffset;
constexpr size_t TraceContextEncoding::kVersionId;

constexpr size_t RpcServerStatsEncoding::kRpcServerStatsSize;
constexpr size_t RpcServerStatsEncoding::kEncodeDecodeFailure;
constexpr size_t RpcServerStatsEncoding::kVersionIdSize;
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169 changes: 0 additions & 169 deletions src/cpp/ext/filters/census/rpc_encoding.h
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Expand Up @@ -31,175 +31,6 @@

namespace grpc {

// TODO(unknown): Rename to GrpcTraceContextV0.
struct GrpcTraceContext {
GrpcTraceContext() {}

explicit GrpcTraceContext(const ::opencensus::trace::SpanContext& ctx) {
ctx.trace_id().CopyTo(trace_id);
ctx.span_id().CopyTo(span_id);
ctx.trace_options().CopyTo(trace_options);
}

::opencensus::trace::SpanContext ToSpanContext() const {
return ::opencensus::trace::SpanContext(
::opencensus::trace::TraceId(trace_id),
::opencensus::trace::SpanId(span_id),
::opencensus::trace::TraceOptions(trace_options));
}

// TODO(unknown): For performance:
// uint8_t version;
// uint8_t trace_id_field_id;
uint8_t trace_id[::opencensus::trace::TraceId::kSize];
// uint8_t span_id_field_id;
uint8_t span_id[::opencensus::trace::SpanId::kSize];
// uint8_t trace_options_field_id;
uint8_t trace_options[::opencensus::trace::TraceOptions::kSize];
};

// TraceContextEncoding encapsulates the logic for encoding and decoding of
// trace contexts.
class TraceContextEncoding {
public:
// Size of encoded GrpcTraceContext. (16 + 8 + 1 + 4)
static constexpr size_t kGrpcTraceContextSize = 29;
// Error value.
static constexpr size_t kEncodeDecodeFailure = 0;

// Deserializes a GrpcTraceContext from the incoming buffer. Returns the
// number of bytes deserialized from the buffer. If the incoming buffer is
// empty or the encoding version is not supported it will return 0 bytes,
// currently only version 0 is supported. If an unknown field ID is
// encountered it will return immediately without parsing the rest of the
// buffer. Inlined for performance reasons.
static size_t Decode(absl::string_view buf, GrpcTraceContext* tc) {
if (buf.empty()) {
return kEncodeDecodeFailure;
}
uint8_t version = buf[kVersionIdOffset];
// TODO(unknown): Support other versions later. Only support version 0 for
// now.
if (version != kVersionId) {
return kEncodeDecodeFailure;
}

size_t pos = kVersionIdSize;
while (pos < buf.size()) {
size_t bytes_read =
ParseField(absl::string_view(&buf[pos], buf.size() - pos), tc);
if (bytes_read == 0) {
break;
} else {
pos += bytes_read;
}
}
return pos;
}

// Serializes a GrpcTraceContext into the provided buffer. Returns the number
// of bytes serialized into the buffer. If the buffer is not of sufficient
// size (it must be at least kGrpcTraceContextSize bytes) it will drop
// everything and return 0 bytes serialized. Inlined for performance reasons.
static size_t Encode(const GrpcTraceContext& tc, char* buf, size_t buf_size) {
if (buf_size < kGrpcTraceContextSize) {
return kEncodeDecodeFailure;
}
buf[kVersionIdOffset] = kVersionId;
buf[kTraceIdOffset] = kTraceIdField;
memcpy(&buf[kTraceIdOffset + 1], tc.trace_id,
opencensus::trace::TraceId::kSize);
buf[kSpanIdOffset] = kSpanIdField;
memcpy(&buf[kSpanIdOffset + 1], tc.span_id,
opencensus::trace::SpanId::kSize);
buf[kTraceOptionsOffset] = kTraceOptionsField;
memcpy(&buf[kTraceOptionsOffset + 1], tc.trace_options,
opencensus::trace::TraceOptions::kSize);
return kGrpcTraceContextSize;
}

private:
// Parses the next field from the incoming buffer and stores the parsed value
// in a GrpcTraceContext struct. If it does not recognize the field ID it
// will return 0, otherwise it returns the number of bytes read.
static size_t ParseField(absl::string_view buf, GrpcTraceContext* tc) {
// TODO(unknown): Add support for multi-byte field IDs.
if (buf.empty()) {
return 0;
}
// Field ID is always the first byte in a field.
uint32_t field_id = buf[0];
size_t bytes_read = kFieldIdSize;
switch (field_id) {
case kTraceIdField:
bytes_read += kTraceIdSize;
if (bytes_read > buf.size()) {
return 0;
}
memcpy(tc->trace_id, &buf[kFieldIdSize],
opencensus::trace::TraceId::kSize);
break;
case kSpanIdField:
bytes_read += kSpanIdSize;
if (bytes_read > buf.size()) {
return 0;
}
memcpy(tc->span_id, &buf[kFieldIdSize],
opencensus::trace::SpanId::kSize);
break;
case kTraceOptionsField:
bytes_read += kTraceOptionsSize;
if (bytes_read > buf.size()) {
return 0;
}
memcpy(tc->trace_options, &buf[kFieldIdSize],
opencensus::trace::TraceOptions::kSize);
break;
default: // Invalid field ID
return 0;
}

return bytes_read;
}

// Size of Version ID.
static constexpr size_t kVersionIdSize = 1;
// Size of Field ID.
static constexpr size_t kFieldIdSize = 1;

// Offset and value for currently supported version ID.
static constexpr size_t kVersionIdOffset = 0;
static constexpr size_t kVersionId = 0;

// Fixed Field ID values:
enum FieldIdValue {
kTraceIdField = 0,
kSpanIdField = 1,
kTraceOptionsField = 2,
};

// Field data sizes in bytes
enum FieldSize {
kTraceIdSize = 16,
kSpanIdSize = 8,
kTraceOptionsSize = 1,
};

// Fixed size offsets for field ID start positions during encoding. Field
// data immediately follows.
enum FieldIdOffset {
kTraceIdOffset = kVersionIdSize,
kSpanIdOffset = kTraceIdOffset + kFieldIdSize + kTraceIdSize,
kTraceOptionsOffset = kSpanIdOffset + kFieldIdSize + kSpanIdSize,
};

TraceContextEncoding() = delete;
TraceContextEncoding(const TraceContextEncoding&) = delete;
TraceContextEncoding(TraceContextEncoding&&) = delete;
TraceContextEncoding operator=(const TraceContextEncoding&) = delete;
TraceContextEncoding operator=(TraceContextEncoding&&) = delete;
};

// TODO(unknown): This may not be needed. Check to see if opencensus requires
// a trailing server response.
// RpcServerStatsEncoding encapsulates the logic for encoding and decoding of
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