introduce two process model (supervisor and child) to accomodate panics
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This commit is contained in:
Emil Lerch 2023-10-26 13:36:36 -07:00
parent 3d3dab9c79
commit fc37764345
Signed by: lobo
GPG Key ID: A7B62D657EF764F8
2 changed files with 49 additions and 8 deletions

1
.gitignore vendored
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@ -1,2 +1,3 @@
zig-cache
zig-out
core

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@ -352,16 +352,56 @@ fn installSignalHandler() !void {
}
pub fn main() !void {
// We are linked to libc, and primarily using the arena allocator
// raw allocator recommended for use in arenas
var raw_allocator = std.heap.raw_c_allocator;
// Our child process will also need an allocator, and is using the
// same pattern, so we will hand the child a raw allocator as well
var child_allocator = std.heap.raw_c_allocator;
// Lastly, we need some of our own operations
var arena = std.heap.ArenaAllocator.init(raw_allocator);
defer arena.deinit();
var parent_allocator = arena.allocator();
var al = std.ArrayList([]const u8).init(parent_allocator);
defer al.deinit();
var argi = std.process.args();
// We do this first so it shows more prominently when looking at processes
// Also it will be slightly faster for whatever that is worth
const child_arg = "--child";
if (argi.next()) |a| try al.append(a);
try al.append(child_arg);
while (argi.next()) |a| {
if (std.mem.eql(u8, child_arg, a)) {
// This should never actually return
return try childMain(child_allocator);
}
try al.append(a);
}
// Parent
const stdin = std.io.getStdIn();
const stdout = std.io.getStdOut();
const stderr = std.io.getStdErr();
while (true) {
// If we use the arena here, we risk a memory leak when our child
// panics. This is because arenas don't actually free memory until
// they deinit. So we need to use the raw allocator here, but the
// arena can be used to store our arguments above
var cp = std.ChildProcess.init(al.items, raw_allocator);
defer cp.deinit();
cp.stdin = stdin;
cp.stdout = stdout;
cp.stderr = stderr;
_ = try cp.spawnAndWait();
try stderr.writeAll("Caught abnormal process termination, relaunching server");
}
}
fn childMain(allocator: std.mem.Allocator) !void {
defer exitApp(1);
// stdout is for the actual output of your application, for example if you
// are implementing gzip, then only the compressed bytes should be sent to
// stdout, not any debugging messages.
// const stdout_file = std.io.getStdOut().writer();
// var bw = std.io.bufferedWriter(stdout_file);
// const stdout = bw.writer();
var allocator = std.heap.raw_c_allocator; // raw allocator recommended for use in arenas
executors = try loadConfig(allocator);
defer allocator.free(executors);
defer parsed_config.deinit();