chromium/third_party/perfetto/src/trace_processor/perfetto_sql/intrinsics/operators/span_join_operator.h

/*
 * Copyright (C) 2018 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.
 */

#ifndef SRC_TRACE_PROCESSOR_PERFETTO_SQL_INTRINSICS_OPERATORS_SPAN_JOIN_OPERATOR_H_
#define SRC_TRACE_PROCESSOR_PERFETTO_SQL_INTRINSICS_OPERATORS_SPAN_JOIN_OPERATOR_H_

#include <cstddef>
#include <cstdint>
#include <limits>
#include <optional>
#include <string>
#include <utility>
#include <vector>

#include "perfetto/base/logging.h"
#include "perfetto/base/status.h"
#include "perfetto/ext/base/flat_hash_map.h"
#include "perfetto/ext/base/string_splitter.h"
#include "perfetto/ext/base/string_utils.h"
#include "perfetto/trace_processor/basic_types.h"
#include "src/trace_processor/sqlite/bindings/sqlite_module.h"
#include "src/trace_processor/sqlite/module_lifecycle_manager.h"
#include "src/trace_processor/sqlite/sqlite_engine.h"

namespace perfetto::trace_processor {

class PerfettoSqlEngine;
struct SpanJoinOperatorModule;

// Implements the SPAN JOIN operation between two tables on a particular column.
//
// Span:
// A span is a row with a timestamp and a duration. It is used to model
// operations which run for a particular *span* of time.
//
// We draw spans like so (time on the x-axis):
// start of span->[ time where opertion is running ]<- end of span
//
// Multiple spans can happen in parallel:
// [      ]
//    [        ]
//   [                    ]
//  [ ]
//
// The above for example, models scheduling activity on a 4-core computer for a
// short period of time.
//
// Span join:
// The span join operation can be thought of as the intersection of span tables.
// That is, the join table has a span for each pair of spans in the child tables
// where the spans overlap. Because many spans are possible in parallel, an
// extra metadata column (labelled the "join column") is used to distinguish
// between the spanned tables.
//
// For a given join key suppose these were the two span tables:
// Table 1:   [        ]              [      ]         [ ]
// Table 2:          [      ]            [  ]           [      ]
// Output :          [ ]                 [  ]           []
//
// All other columns apart from timestamp (ts), duration (dur) and the join key
// are passed through unchanged.
struct SpanJoinOperatorModule : public sqlite::Module<SpanJoinOperatorModule> { … };

}  // namespace perfetto::trace_processor

#endif  // SRC_TRACE_PROCESSOR_PERFETTO_SQL_INTRINSICS_OPERATORS_SPAN_JOIN_OPERATOR_H_