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Diffstat (limited to 'src/mongo/db/ftdc/decompressor.cpp')
| -rw-r--r-- | src/mongo/db/ftdc/decompressor.cpp | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/src/mongo/db/ftdc/decompressor.cpp b/src/mongo/db/ftdc/decompressor.cpp new file mode 100644 index 00000000000..91a3d48f65c --- /dev/null +++ b/src/mongo/db/ftdc/decompressor.cpp @@ -0,0 +1,169 @@ +/** + * Copyright (C) 2015 MongoDB Inc. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU Affero General Public License, version 3, + * as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + * As a special exception, the copyright holders give permission to link the + * code of portions of this program with the OpenSSL library under certain + * conditions as described in each individual source file and distribute + * linked combinations including the program with the OpenSSL library. You + * must comply with the GNU Affero General Public License in all respects + * for all of the code used other than as permitted herein. If you modify + * file(s) with this exception, you may extend this exception to your + * version of the file(s), but you are not obligated to do so. If you do not + * wish to do so, delete this exception statement from your version. If you + * delete this exception statement from all source files in the program, + * then also delete it in the license file. + */ + +#include "mongo/platform/basic.h" + +#include "mongo/db/ftdc/decompressor.h" + +#include "mongo/base/data_range_cursor.h" +#include "mongo/base/data_type_validated.h" +#include "mongo/db/ftdc/compressor.h" +#include "mongo/db/ftdc/util.h" +#include "mongo/db/ftdc/varint.h" +#include "mongo/db/jsobj.h" +#include "mongo/util/assert_util.h" + +namespace mongo { + +StatusWith<std::vector<BSONObj>> FTDCDecompressor::uncompress(ConstDataRange buf) { + ConstDataRangeCursor cdc(buf); + + // The document is not part of any checksum so we must validate it is correct + auto swRef = cdc.readAndAdvance<Validated<BSONObj>>(); + if (!swRef.isOK()) { + return {swRef.getStatus()}; + } + + BSONObj ref = swRef.getValue(); + + // Read count of metrics + auto swMetricsCount = cdc.readAndAdvance<LittleEndian<std::uint32_t>>(); + if (!swMetricsCount.isOK()) { + return {swMetricsCount.getStatus()}; + } + + std::uint32_t metricsCount = swMetricsCount.getValue(); + + // Read count of samples + auto swSampleCount = cdc.readAndAdvance<LittleEndian<std::uint32_t>>(); + if (!swSampleCount.isOK()) { + return {swSampleCount.getStatus()}; + } + + std::uint32_t sampleCount = swSampleCount.getValue(); + + // Limit size of the buffer we need for metrics and samples + if (metricsCount * sampleCount > 1000000) { + return Status(ErrorCodes::InvalidLength, + "Metrics Count and Sample Count have exceeded the allowable range."); + } + + std::vector<std::uint64_t> metrics; + + metrics.reserve(metricsCount); + + // We pass the reference document as both the reference document and current document as we only + // want the array of metrics. + (void)FTDCBSONUtil::extractMetricsFromDocument(ref, ref, &metrics); + + if (metrics.size() != metricsCount) { + return {ErrorCodes::BadValue, + "The metrics in the reference document and metrics count do not match"}; + } + + std::vector<BSONObj> docs; + + // Allocate space for the reference document + samples + docs.reserve(1 + sampleCount); + + docs.emplace_back(ref); + + // We must always return the reference document + if (sampleCount == 0) { + return {docs}; + } + + // Decompress the zlib compressed buffer + size_t expectedDestLength = metricsCount * sampleCount * FTDCVarInt::kMaxSizeBytes64; + + auto statusUncompress = _compressor.uncompress(cdc, expectedDestLength); + + if (!statusUncompress.isOK()) { + return {statusUncompress.getStatus()}; + } + + // Read the samples + std::vector<std::uint64_t> deltas(metricsCount * sampleCount); + + // decompress the deltas + std::uint64_t zeroesCount = 0; + + auto cdrc = ConstDataRangeCursor(statusUncompress.getValue()); + + for (std::uint32_t i = 0; i < metricsCount; i++) { + for (std::uint32_t j = 0; j < sampleCount; j++) { + if (zeroesCount) { + deltas[FTDCCompressor::getArrayOffset(sampleCount, j, i)] = 0; + zeroesCount--; + continue; + } + + auto swDelta = cdrc.readAndAdvance<FTDCVarInt>(); + + if (!swDelta.isOK()) { + return swDelta.getStatus(); + } + + if (swDelta.getValue() == 0) { + auto swZero = cdrc.readAndAdvance<FTDCVarInt>(); + + if (!swZero.isOK()) { + return swDelta.getStatus(); + } + + zeroesCount = swZero.getValue(); + } + + deltas[FTDCCompressor::getArrayOffset(sampleCount, j, i)] = swDelta.getValue(); + } + } + + // Inflate the deltas + for (std::uint32_t i = 0; i < metricsCount; i++) { + deltas[FTDCCompressor::getArrayOffset(sampleCount, 0, i)] += metrics[i]; + } + + for (std::uint32_t i = 0; i < metricsCount; i++) { + for (std::uint32_t j = 1; j < sampleCount; j++) { + deltas[FTDCCompressor::getArrayOffset(sampleCount, j, i)] += + deltas[FTDCCompressor::getArrayOffset(sampleCount, j - 1, i)]; + } + } + + for (std::uint32_t i = 0; i < sampleCount; ++i) { + for (std::uint32_t j = 0; j < metricsCount; ++j) { + metrics[j] = deltas[j * sampleCount + i]; + } + + docs.emplace_back(FTDCBSONUtil::constructDocumentFromMetrics(ref, metrics).getValue()); + } + + return {docs}; +} + +} // namespace mongo |