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80c663882a
Summary: First draft. Unit tests pass. Test Plan: unit tests attached Reviewers: heyongqiang Reviewed By: heyongqiang Differential Revision: https://reviews.facebook.net/D3969
97 lines
2.8 KiB
C++
97 lines
2.8 KiB
C++
/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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#ifndef _THRIFT_TREFLECTIONLOCAL_H_
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#define _THRIFT_TREFLECTIONLOCAL_H_ 1
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#include <stdint.h>
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#include <cstring>
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#include "thrift/lib/cpp/protocol/TProtocol.h"
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/**
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* Local Reflection is a blanket term referring to the the structure
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* and generation of this particular representation of Thrift types.
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* (It is called local because it cannot be serialized by Thrift).
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*
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*/
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namespace apache { namespace thrift { namespace reflection { namespace local {
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using apache::thrift::protocol::TType;
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// We include this many bytes of the structure's fingerprint when serializing
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// a top-level structure. Long enough to make collisions unlikely, short
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// enough to not significantly affect the amount of memory used.
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const int FP_PREFIX_LEN = 4;
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struct FieldMeta {
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int16_t tag;
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bool is_optional;
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};
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struct TypeSpec {
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TType ttype;
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uint8_t fp_prefix[FP_PREFIX_LEN];
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// Use an anonymous union here so we can fit two TypeSpecs in one cache line.
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union {
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struct {
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// Use parallel arrays here for denser packing (of the arrays).
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FieldMeta* metas;
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TypeSpec** specs;
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} tstruct;
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struct {
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TypeSpec *subtype1;
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TypeSpec *subtype2;
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} tcontainer;
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};
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// Static initialization of unions isn't really possible,
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// so take the plunge and use constructors.
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// Hopefully they'll be evaluated at compile time.
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TypeSpec(TType ttype) : ttype(ttype) {
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std::memset(fp_prefix, 0, FP_PREFIX_LEN);
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}
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TypeSpec(TType ttype,
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const uint8_t* fingerprint,
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FieldMeta* metas,
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TypeSpec** specs) :
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ttype(ttype)
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{
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std::memcpy(fp_prefix, fingerprint, FP_PREFIX_LEN);
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tstruct.metas = metas;
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tstruct.specs = specs;
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}
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TypeSpec(TType ttype, TypeSpec* subtype1, TypeSpec* subtype2) :
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ttype(ttype)
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{
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std::memset(fp_prefix, 0, FP_PREFIX_LEN);
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tcontainer.subtype1 = subtype1;
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tcontainer.subtype2 = subtype2;
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}
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};
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}}}} // apache::thrift::reflection::local
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#endif // #ifndef _THRIFT_TREFLECTIONLOCAL_H_
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