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/*
* Copyright (C) 2019 The Android Open Source Project
*
* 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.
*/
// For bazel build.
#include "perfetto/base/build_config.h"
#if PERFETTO_BUILDFLAG(PERFETTO_TP_JSON_IMPORT)
#include "src/trace_processor/importers/json/json_trace_tokenizer.h"
#include <json/reader.h>
#include <json/value.h>
#include "src/trace_processor/importers/json/json_trace_utils.h"
#include "src/trace_processor/stats.h"
#include "src/trace_processor/trace_blob_view.h"
#include "src/trace_processor/trace_sorter.h"
namespace perfetto {
namespace trace_processor {
// Parses at most one JSON dictionary and returns a pointer to the end of it,
// or nullptr if no dict could be detected.
// This is to avoid decoding the full trace in memory and reduce heap traffic.
// E.g. input: { a:1 b:{ c:2, d:{ e:3 } } } , { a:4, ... },
// output: [ only this is parsed ] ^return value points here.
ReadDictRes ReadOneJsonDict(const char* start,
const char* end,
Json::Value* value,
const char** next) {
int braces = 0;
int square_brackets = 0;
const char* dict_begin = nullptr;
bool in_string = false;
bool is_escaping = false;
for (const char* s = start; s < end; s++) {
if (isspace(*s) || *s == ',')
continue;
if (*s == '"' && !is_escaping) {
in_string = !in_string;
continue;
}
if (in_string) {
// If we're in a string and we see a backslash and the last character was
// not a backslash the next character is escaped:
is_escaping = *s == '\\' && !is_escaping;
// If we're currently parsing a string we should ignore otherwise special
// characters:
continue;
}
if (*s == '{') {
if (braces == 0)
dict_begin = s;
braces++;
continue;
}
if (*s == '}') {
if (braces <= 0)
return kEndOfTrace;
if (--braces > 0)
continue;
Json::Reader reader;
if (!reader.parse(dict_begin, s + 1, *value, /*collectComments=*/false)) {
PERFETTO_ELOG("JSON error: %s",
reader.getFormattedErrorMessages().c_str());
return kFatalError;
}
*next = s + 1;
return kFoundDict;
}
if (*s == '[') {
square_brackets++;
continue;
}
if (*s == ']') {
if (square_brackets == 0) {
// We've reached the end of [traceEvents] array.
// There might be other top level keys in the json (e.g. metadata)
// after.
// TODO(dproy): Handle trace metadata importing.
return kEndOfTrace;
}
square_brackets--;
}
}
return kNeedsMoreData;
}
JsonTraceTokenizer::JsonTraceTokenizer(TraceProcessorContext* ctx)
: context_(ctx) {}
JsonTraceTokenizer::~JsonTraceTokenizer() = default;
util::Status JsonTraceTokenizer::Parse(std::unique_ptr<uint8_t[]> data,
size_t size) {
buffer_.insert(buffer_.end(), data.get(), data.get() + size);
const char* buf = buffer_.data();
const char* next = buf;
const char* end = buf + buffer_.size();
if (offset_ == 0) {
// Trace could begin in any of these ways:
// {"traceEvents":[{
// { "traceEvents": [{
// [{
// Skip up to the first '['
while (next != end && *next != '[') {
next++;
}
if (next == end)
return util::ErrStatus("Failed to parse: first chunk missing opening [");
next++;
}
auto* trace_sorter = context_->sorter.get();
while (next < end) {
std::unique_ptr<Json::Value> value(new Json::Value());
const auto res = ReadOneJsonDict(next, end, value.get(), &next);
if (res == kFatalError)
return util::ErrStatus("Encountered fatal error while parsing JSON");
if (res == kEndOfTrace || res == kNeedsMoreData)
break;
base::Optional<int64_t> opt_ts =
json_trace_utils::CoerceToNs((*value)["ts"]);
if (!opt_ts.has_value()) {
context_->storage->IncrementStats(stats::json_tokenizer_failure);
continue;
}
int64_t ts = opt_ts.value();
trace_sorter->PushJsonValue(ts, std::move(value));
}
offset_ += static_cast<uint64_t>(next - buf);
buffer_.erase(buffer_.begin(), buffer_.begin() + (next - buf));
return util::OkStatus();
}
} // namespace trace_processor
} // namespace perfetto
#endif // PERFETTO_BUILDFLAG(PERFETTO_TP_JSON_IMPORT)
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