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Joyee Cheung be525d7d04 src: consolidate exit codes in the code base Add an ExitCode enum class and use it throughout the code base instead of hard-coding the exit codes everywhere. At the moment, the exit codes used in many places do not actually conform to what the documentation describes. With the new enums (which are also available to the JS land as constants in an internal binding) we could migrate to a more consistent usage of the codes, and eventually expose the constants to the user land when they are stable enough. PR-URL: https://github.com/nodejs/node/pull/44746 Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com> Reviewed-By: Jacob Smith <jacob@frende.me> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Darshan Sen <raisinten@gmail.com>	2022-10-06 12:41:16 +00:00
..
node_mksnapshot.cc	src: consolidate exit codes in the code base	2022-10-06 12:41:16 +00:00
README.md	bootstrap: use SnapshotData to pass snapshot data around	2022-03-23 20:20:14 +08:00

src: consolidate exit codes in the code base

Add an ExitCode enum class and use it throughout the code base
instead of hard-coding the exit codes everywhere. At the moment,
the exit codes used in many places do not actually conform to
what the documentation describes. With the new enums (which
are also available to the JS land as constants in an internal
binding) we could migrate to a more consistent usage of the
codes, and eventually expose the constants to the user land
when they are stable enough.

PR-URL: https://github.com/nodejs/node/pull/44746
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Jacob Smith <jacob@frende.me>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>

2022-10-06 12:41:16 +00:00

node_mksnapshot.cc

src: consolidate exit codes in the code base

2022-10-06 12:41:16 +00:00

README.md

bootstrap: use SnapshotData to pass snapshot data around

2022-03-23 20:20:14 +08:00

README.md

Node.js startup snapshot builder

This is the V8 startup snapshot builder of Node.js. Not to be confused with V8's own snapshot builder, which builds a snapshot containing JavaScript builtins, this builds a snapshot containing Node.js builtins that can be deserialized on top of V8's own startup snapshot. When Node.js is launched, instead of executing code to bootstrap, it can deserialize the context from an embedded snapshot, which readily contains the result of the bootstrap, so that Node.js can start up faster.

Currently only the main context of the main Node.js instance supports snapshot deserialization, and the snapshot does not yet cover the entire bootstrap process. Work is being done to expand the support.

How it's built and used

The snapshot builder is built with the node_mksnapshot target in node.gyp when node_use_node_snapshot is set to true, which is currently done by default.

In the default build of the Node.js executable, to embed a V8 startup snapshot into the Node.js executable, libnode is first built with these unresolved symbols:

node::NodeMainInstance::GetEmbeddedSnapshotData

Then the node_mksnapshot executable is built with C++ files in this directory, as well as src/node_snapshot_stub.cc which defines the unresolved symbols.

node_mksnapshot is run to generate a C++ file <(SHARED_INTERMEDIATE_DIR)/node_snapshot.cc that is similar to src/node_snapshot_stub.cc in structure, but contains the snapshot data written as static char array literals. Then libnode is built with node_snapshot.cc to produce the final Node.js executable with the snapshot data embedded.

For debugging, Node.js can be built without Node.js's own snapshot if --without-node-snapshot is passed to configure. A Node.js executable with Node.js snapshot embedded can also be launched without deserializing from it if the command line argument --no-node-snapshot is passed.