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/* -*- Mode: protobuf; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
// # Core Dumps
//
// A core dump is a serialized snapshot of the heap graph. We serialize the heap
// as a series of protobuf messages with each message prefixed by its Varint32
// byte size so we can delimit individual protobuf messages (protobuf parsers
// cannot determine where a message ends on their own).
//
// The first protobuf message is an instance of the `Metadata` message. All
// subsequent messages will be instances of the `Node` message. The first of
// these `Node` messages is the root node of the serialized heap graph. Here is
// a diagram of our core dump format:
//
// +-----------------------------------------------------------------------+
// | Varint32: The size of following `Metadata` message. |
// +-----------------------------------------------------------------------+
// | message: The core dump `Metadata` message. |
// +-----------------------------------------------------------------------+
// | Varint32: The size of the following `Node` message. |
// +-----------------------------------------------------------------------+
// | message: The first `Node` message. This is the root node. |
// +-----------------------------------------------------------------------+
// | Varint32: The size of the following `Node` message. |
// +-----------------------------------------------------------------------+
// | message: A `Node` message. |
// +-----------------------------------------------------------------------+
// | Varint32: The size of the following `Node` message. |
// +-----------------------------------------------------------------------+
// | message: A `Node` message. |
// +-----------------------------------------------------------------------+
// | . |
// | . |
// | . |
// +-----------------------------------------------------------------------+
//
// Core dumps should always be written with a
// `google::protobuf::io::GzipOutputStream` and read from a
// `google::protobuf::io::GzipInputStream`.
//
// Note that all strings are de-duplicated. The first time the N^th unique
// string is encountered, the full string is serialized. Subsequent times that
// same string is encountered, it is referenced by N. This de-duplication
// happens across string properties, not on a per-property basis. For example,
// if the same K^th unique string is first used as an Edge::EdgeNameOrRef and
// then as a StackFrame::Data::FunctionDisplayNameOrRef, the first will be the
// actual string as the functionDisplayName oneof property, and the second will
// be a reference to the first as the edgeNameRef oneof property whose value is
// K.
//
// We would ordinarily abstract these de-duplicated strings with messages of
// their own, but unfortunately, the protobuf compiler does not have a way to
// inline a messsage within another message and the child message must be
// referenced by pointer. This leads to extra mallocs that we wish to avoid.
package mozilla.devtools.protobuf;
// A collection of metadata about this core dump.
message Metadata {
// Number of microseconds since midnight (00:00:00) 1 January 1970 UTC.
optional uint64 timeStamp = 1;
}
// A serialized version of `JS::ubi::StackFrame`. Older parent frame tails are
// de-duplicated to cut down on [de]serialization and size costs.
message StackFrame {
oneof StackFrameType {
// This is the first time this stack frame has been serialized, and so
// here is all of its data.
Data data = 1;
// A reference to a stack frame that has already been serialized and has
// the given number as its id.
uint64 ref = 2;
}
message Data {
optional uint64 id = 1;
optional StackFrame parent = 2;
optional uint32 line = 3;
optional uint32 column = 4;
// De-duplicated two-byte string.
oneof SourceOrRef {
bytes source = 5;
uint64 sourceRef = 6;
}
// De-duplicated two-byte string.
oneof FunctionDisplayNameOrRef {
bytes functionDisplayName = 7;
uint64 functionDisplayNameRef = 8;
}
optional bool isSystem = 9;
optional bool isSelfHosted = 10;
}
}
// A serialized version of `JS::ubi::Node` and its outgoing edges.
message Node {
optional uint64 id = 1;
// De-duplicated two-byte string.
oneof TypeNameOrRef {
bytes typeName = 2;
uint64 typeNameRef = 3;
}
optional uint64 size = 4;
repeated Edge edges = 5;
optional StackFrame allocationStack = 6;
// De-duplicated one-byte string.
oneof JSObjectClassNameOrRef {
bytes jsObjectClassName = 7;
uint64 jsObjectClassNameRef = 8;
}
// JS::ubi::CoarseType. Defaults to Other.
optional uint32 coarseType = 9 [default = 0];
// De-duplicated one-byte string.
oneof ScriptFilenameOrRef {
bytes scriptFilename = 10;
uint64 scriptFilenameRef = 11;
}
}
// A serialized edge from the heap graph.
message Edge {
optional uint64 referent = 1;
// De-duplicated two-byte string.
oneof EdgeNameOrRef {
bytes name = 2;
uint64 nameRef = 3;
}
}
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