diff options
author | Feng Xiao <xfxyjwf@gmail.com> | 2016-07-13 13:47:51 -0700 |
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committer | Feng Xiao <xfxyjwf@gmail.com> | 2016-07-13 13:48:40 -0700 |
commit | 9086d9643903c608ab015b0b7d903547a4e7b6f3 (patch) | |
tree | b47053ab6f6bde20b55c4fff4019c68a7c45545c /src/google/protobuf/io/coded_stream.h | |
parent | 70c1ac756d3cd8fa04725f82f0ad1a30404c3bb3 (diff) |
Integrate from internal code base.
Diffstat (limited to 'src/google/protobuf/io/coded_stream.h')
-rw-r--r-- | src/google/protobuf/io/coded_stream.h | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/src/google/protobuf/io/coded_stream.h b/src/google/protobuf/io/coded_stream.h index eb320745..316da765 100644 --- a/src/google/protobuf/io/coded_stream.h +++ b/src/google/protobuf/io/coded_stream.h @@ -813,6 +813,44 @@ class LIBPROTOBUF_EXPORT CodedOutputStream { // created. bool HadError() const { return had_error_; } + // Deterministic serialization, if requested, guarantees that for a given + // binary, equal messages will always be serialized to the same bytes. This + // implies: + // . repeated serialization of a message will return the same bytes + // . different processes of the same binary (which may be executing on + // different machines) will serialize equal messages to the same bytes. + // + // Note the deterministic serialization is NOT canonical across languages; it + // is also unstable across different builds with schema changes due to unknown + // fields. Users who need canonical serialization, e.g., persistent storage in + // a canonical form, fingerprinting, etc., should define their own + // canonicalization specification and implement the serializer using + // reflection APIs rather than relying on this API. + // + // If determinisitc serialization is requested, the serializer will + // sort map entries by keys in lexicographical order or numerical order. + // (This is an implementation detail and may subject to change.) + // + // There are two ways to determine whether serialization should be + // deterministic for this CodedOutputStream. If SetSerializationDeterministic + // has not yet been called, then the default comes from the global default, + // which is false, until SetDefaultSerializationDeterministic has been called. + // Otherwise, SetSerializationDeterministic has been called, and the last + // value passed to it is all that matters. + void SetSerializationDeterministic(bool value) { + serialization_deterministic_is_overridden_ = true; + serialization_deterministic_override_ = value; + } + // See above. Also, note that users of this CodedOutputStream may need to + // call IsSerializationDeterminstic() to serialize in the intended way. This + // CodedOutputStream cannot enforce a desire for deterministic serialization + // by itself. + bool IsSerializationDeterminstic() const { + return serialization_deterministic_is_overridden_ ? + serialization_deterministic_override_ : + default_serialization_deterministic_; + } + private: GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CodedOutputStream); @@ -822,6 +860,10 @@ class LIBPROTOBUF_EXPORT CodedOutputStream { int total_bytes_; // Sum of sizes of all buffers seen so far. bool had_error_; // Whether an error occurred during output. bool aliasing_enabled_; // See EnableAliasing(). + // See SetSerializationDeterministic() regarding these three fields. + bool serialization_deterministic_is_overridden_; + bool serialization_deterministic_override_; + static bool default_serialization_deterministic_; // Advance the buffer by a given number of bytes. void Advance(int amount); @@ -849,6 +891,11 @@ class LIBPROTOBUF_EXPORT CodedOutputStream { uint64 value, uint8* target); static int VarintSize32Fallback(uint32 value); + + // See above. Other projects may use "friend" to allow them to call this. + static void SetDefaultSerializationDeterministic() { + default_serialization_deterministic_ = true; + } }; // inline methods ==================================================== |