New class StructuredProtoField

PiperOrigin-RevId: 711892840
Change-Id: I2321e83e2939d21836ba1df335b2e97366594076

CMake/AbseilDll.cmake

@@ -193,6 +193,8 @@ set(ABSL_INTERNAL_DLL_FILES
   "log/internal/proto.cc"
   "log/internal/strip.h"
   "log/internal/structured.h"
+  "log/internal/structured_proto.cc"
+  "log/internal/structured_proto.h"
   "log/internal/vlog_config.cc"
   "log/internal/vlog_config.h"
   "log/internal/voidify.h"

absl/log/CMakeLists.txt

@@ -672,6 +672,44 @@ absl_cc_library(
     absl::strings
 )
 
+absl_cc_library(
+  NAME
+    log_internal_structured_proto
+  SRCS
+    "internal/structured_proto.cc"
+  HDRS
+    "internal/structured_proto.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::log_internal_proto
+    absl::config
+    absl::span
+    absl::strings
+    absl::variant
+  PUBLIC
+)
+
+absl_cc_test(
+  NAME
+    log_internal_structured_proto_test
+  SRCS
+    "internal/structured_proto_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::log_internal_structured_proto
+    absl::span
+    absl::string_view
+    absl::utility
+    GTest::gmock_main
+)
+
 absl_cc_library(
   NAME
     log_structured

absl/log/internal/BUILD.bazel

@@ -34,6 +34,13 @@ package(
 
 licenses(["notice"])
 
+package_group(
+    name = "structured_proto_users",
+    packages = [
+        "//absl/log/...",
+    ],
+)
+
 cc_library(
     name = "check_impl",
     hdrs = ["check_impl.h"],
@@ -288,6 +295,38 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "structured_proto",
+    srcs = ["structured_proto.cc"],
+    hdrs = ["structured_proto.h"],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    visibility = [
+        ":structured_proto_users",
+    ],
+    deps = [
+        ":proto",
+        "//absl/base:config",
+        "//absl/strings",
+        "//absl/types:span",
+        "//absl/types:variant",
+    ],
+)
+
+cc_test(
+    name = "structured_proto_test",
+    srcs = ["structured_proto_test.cc"],
+    deps = [
+        ":structured_proto",
+        "//absl/base:config",
+        "//absl/strings:string_view",
+        "//absl/types:span",
+        "//absl/utility",
+        "@googletest//:gtest",
+        "@googletest//:gtest_main",
+    ],
+)
+
 cc_library(
     name = "test_actions",
     testonly = True,

absl/log/internal/structured_proto.cc

@@ -0,0 +1,115 @@
+//
+// Copyright 2024 The Abseil 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
+//
+//      https://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.
+
+#include "absl/log/internal/structured_proto.h"
+
+#include <cstdint>
+
+#include "absl/base/config.h"
+#include "absl/log/internal/proto.h"
+#include "absl/types/span.h"
+#include "absl/types/variant.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace log_internal {
+
+namespace {
+
+// Handles protobuf-encoding a type contained inside
+// `StructuredProtoField::Varint`.
+struct VarintEncoderVisitor final {
+  template <typename T>
+  bool operator()(T value) const {
+    return EncodeVarint(field_number, value, &buf);
+  }
+
+  uint64_t field_number;
+  absl::Span<char>& buf;
+};
+
+// Handles protobuf-encoding a type contained inside
+// `StructuredProtoField::I64`.
+struct I64EncoderVisitor final {
+  bool operator()(uint64_t value) const {
+    return Encode64Bit(field_number, value, &buf);
+  }
+
+  bool operator()(int64_t value) const {
+    return Encode64Bit(field_number, value, &buf);
+  }
+
+  bool operator()(double value) const {
+    return EncodeDouble(field_number, value, &buf);
+  }
+
+  uint64_t field_number;
+  absl::Span<char>& buf;
+};
+
+// Handles protobuf-encoding a type contained inside
+// `StructuredProtoField::I32`.
+struct I32EncoderVisitor final {
+  bool operator()(uint32_t value) const {
+    return Encode32Bit(field_number, value, &buf);
+  }
+
+  bool operator()(int32_t value) const {
+    return Encode32Bit(field_number, value, &buf);
+  }
+
+  bool operator()(float value) const {
+    return EncodeFloat(field_number, value, &buf);
+  }
+
+  uint64_t field_number;
+  absl::Span<char>& buf;
+};
+
+// Handles protobuf-encoding a type contained inside `StructuredProtoField`.
+struct EncoderVisitor final {
+  bool operator()(StructuredProtoField::Varint varint) {
+    return absl::visit(VarintEncoderVisitor{field_number, buf}, varint);
+  }
+
+  bool operator()(StructuredProtoField::I64 i64) {
+    return absl::visit(I64EncoderVisitor{field_number, buf}, i64);
+  }
+
+  bool operator()(StructuredProtoField::LengthDelimited length_delimited) {
+    // No need for a visitor, since `StructuredProtoField::LengthDelimited` is
+    // just `absl::Span<const char>`.
+    return EncodeBytes(field_number, length_delimited, &buf);
+  }
+
+  bool operator()(StructuredProtoField::I32 i32) {
+    return absl::visit(I32EncoderVisitor{field_number, buf}, i32);
+  }
+
+  uint64_t field_number;
+  absl::Span<char>& buf;
+};
+
+}  // namespace
+
+bool EncodeStructuredProtoField(StructuredProtoField field,
+                                absl::Span<char>& buf) {
+  return absl::visit(EncoderVisitor{field.field_number, buf}, field.value);
+}
+
+}  // namespace log_internal
+
+ABSL_NAMESPACE_END
+}  // namespace absl

absl/log/internal/structured_proto.h

@@ -0,0 +1,107 @@
+// Copyright 2024 The Abseil 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
+//
+//      https://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.
+//
+// -----------------------------------------------------------------------------
+// File: log/internal/structured_proto.h
+// -----------------------------------------------------------------------------
+
+#ifndef ABSL_LOG_INTERNAL_STRUCTURED_PROTO_H_
+#define ABSL_LOG_INTERNAL_STRUCTURED_PROTO_H_
+
+#include <cstddef>
+#include <cstdint>
+
+#include "absl/base/config.h"
+#include "absl/log/internal/proto.h"
+#include "absl/types/span.h"
+#include "absl/types/variant.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace log_internal {
+
+// Sum type holding a single valid protobuf field suitable for encoding.
+struct StructuredProtoField final {
+  // Numeric type encoded with varint encoding:
+  // https://protobuf.dev/programming-guides/encoding/#varints
+  using Varint = absl::variant<uint64_t, int64_t, uint32_t, int32_t, bool>;
+
+  // Fixed-length 64-bit integer encoding:
+  // https://protobuf.dev/programming-guides/encoding/#non-varints
+  using I64 = absl::variant<uint64_t, int64_t, double>;
+
+  // Length-delimited record type (string, sub-message):
+  // https://protobuf.dev/programming-guides/encoding/#length-types
+  using LengthDelimited = absl::Span<const char>;
+
+  // Fixed-length 32-bit integer encoding:
+  // https://protobuf.dev/programming-guides/encoding/#non-varints
+  using I32 = absl::variant<uint32_t, int32_t, float>;
+
+  // Valid record type:
+  // https://protobuf.dev/programming-guides/encoding/#structure
+  using Value = absl::variant<Varint, I64, LengthDelimited, I32>;
+
+  // Field number for the protobuf value.
+  uint64_t field_number;
+
+  // Value to encode.
+  Value value;
+};
+
+// Estimates the number of bytes needed to encode `field` using
+// protobuf encoding.
+//
+// The returned value might be larger than the actual number of bytes needed.
+inline size_t BufferSizeForStructuredProtoField(StructuredProtoField field) {
+  // Visitor to estimate the number of bytes of one of the types contained
+  // inside `StructuredProtoField`.
+  struct BufferSizeVisitor final {
+    size_t operator()(StructuredProtoField::Varint /*unused*/) {
+      return BufferSizeFor(field_number, WireType::kVarint);
+    }
+
+    size_t operator()(StructuredProtoField::I64 /*unused*/) {
+      return BufferSizeFor(field_number, WireType::k64Bit);
+    }
+
+    size_t operator()(StructuredProtoField::LengthDelimited length_delimited) {
+      return BufferSizeFor(field_number, WireType::kLengthDelimited) +
+             length_delimited.size();
+    }
+
+    size_t operator()(StructuredProtoField::I32 /*unused*/) {
+      return BufferSizeFor(field_number, WireType::k32Bit);
+    }
+
+    uint64_t field_number;
+  };
+
+  return absl::visit(BufferSizeVisitor{field.field_number}, field.value);
+}
+
+// Encodes `field` into `buf` using protobuf encoding.
+//
+// On success, returns `true` and advances `buf` to the end of
+// the bytes consumed.
+//
+// On failure (if `buf` was too small), returns `false`.
+bool EncodeStructuredProtoField(StructuredProtoField field,
+                                absl::Span<char>& buf);
+
+}  // namespace log_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_LOG_INTERNAL_STRUCTURED_PROTO_H_