Add support for multithreaded scanning to JSON export

by scanning into memory first.

src/json_import.zig

@@ -306,7 +306,6 @@ test "JSON parser" {
 const Ctx = struct {
     p: *Parser,
     sink: *sink.Thread,
-    items_seen: u64 = 0,
     stat: sink.Stat = .{},
     special: ?sink.Special = null,
     namelen: usize = 0,
@@ -457,8 +456,7 @@ fn item(ctx: *Ctx, parent: ?*sink.Dir, dev: u64) void {
         parent.?.addStat(ctx.sink, name, &ctx.stat);
     }
 
-    ctx.items_seen += 1;
-    if ((ctx.items_seen & 1023) == 0)
+    if ((ctx.sink.files_seen.load(.monotonic) & 1024) == 0)
         main.handleEvent(false, false);
 }
 

src/mem_src.zig

@@ -0,0 +1,79 @@
+// SPDX-FileCopyrightText: Yorhel <projects@yorhel.nl>
+// SPDX-License-Identifier: MIT
+
+const std = @import("std");
+const main = @import("main.zig");
+const model = @import("model.zig");
+const sink = @import("sink.zig");
+
+// Emit the memory tree to the sink in depth-first order from a single thread,
+// suitable for JSON export.
+
+fn toStat(e: *model.Entry) sink.Stat {
+    const el = e.link();
+    return sink.Stat{
+        .blocks = e.pack.blocks,
+        .size = e.size,
+        .dev =
+            if (e.dir()) |d| model.devices.list.items[d.pack.dev]
+            else if (el) |l| model.devices.list.items[l.parent.pack.dev]
+            else undefined,
+        .ino = if (el) |l| l.ino else undefined,
+        .nlink = if (el) |l| l.pack.nlink else undefined,
+        .hlinkc = el != null,
+        .dir = e.pack.etype == .dir,
+        .reg = if (e.file()) |f| !f.pack.notreg else e.pack.etype != .dir,
+        .symlink = undefined,
+        .ext = if (e.ext()) |x| x.* else .{},
+    };
+}
+
+const Ctx = struct {
+    sink: *sink.Thread,
+    stat: sink.Stat,
+};
+
+
+fn rec(ctx: *Ctx, dir: *sink.Dir, entry: *model.Entry) void {
+    if ((ctx.sink.files_seen.load(.monotonic) & 1024) == 0)
+        main.handleEvent(false, false);
+
+    ctx.stat = toStat(entry);
+    if (entry.dir()) |d| {
+        var ndir = dir.addDir(ctx.sink, entry.name(), &ctx.stat);
+        ctx.sink.setDir(ndir);
+        if (d.pack.err) ndir.setReadError(ctx.sink);
+        var it = d.sub;
+        while (it) |e| : (it = e.next) rec(ctx, ndir, e);
+        ctx.sink.setDir(dir);
+        ndir.unref();
+        return;
+    }
+    if (entry.file()) |f| {
+        if (f.pack.err) return dir.addSpecial(ctx.sink, entry.name(), .err);
+        if (f.pack.excluded) return dir.addSpecial(ctx.sink, entry.name(), .excluded);
+        if (f.pack.other_fs) return dir.addSpecial(ctx.sink, entry.name(), .other_fs);
+        if (f.pack.kernfs) return dir.addSpecial(ctx.sink, entry.name(), .kernfs);
+    }
+    dir.addStat(ctx.sink, entry.name(), &ctx.stat);
+}
+
+
+pub fn run(d: *model.Dir) void {
+    const sink_threads = sink.createThreads(1);
+
+    var ctx = .{
+        .sink = &sink_threads[0],
+        .stat = toStat(&d.entry),
+    };
+    var buf = std.ArrayList(u8).init(main.allocator);
+    d.fmtPath(true, &buf);
+    const root = sink.createRoot(buf.items, &ctx.stat);
+    buf.deinit();
+
+    var it = d.sub;
+    while (it) |e| : (it = e.next) rec(&ctx, root, e);
+
+    root.unref();
+    sink.done();
+}

src/sink.zig

@@ -4,6 +4,7 @@
 const std = @import("std");
 const main = @import("main.zig");
 const model = @import("model.zig");
+const mem_src = @import("mem_src.zig");
 const ui = @import("ui.zig");
 const util = @import("util.zig");
 
@@ -267,6 +268,7 @@ const MemDir = struct {
     }
 
     fn addStat(self: *MemDir, alloc: std.mem.Allocator, name: []const u8, stat: *const Stat) *model.Entry {
+        if (state.defer_json == null) {
             self.dir.items +|= 1;
             if (!stat.hlinkc) {
                 self.dir.entry.pack.blocks +|= stat.blocks;
@@ -275,6 +277,7 @@ const MemDir = struct {
             if (self.dir.entry.ext()) |e| {
                 if (stat.ext.mtime > e.mtime) e.mtime = stat.ext.mtime;
             }
+        }
 
         const etype = if (stat.dir) model.EType.dir
                       else if (stat.hlinkc) model.EType.link
@@ -312,6 +315,9 @@ const MemDir = struct {
                 else it = &e.next;
             }
         }
+        self.entries.deinit();
+
+        if (state.defer_json != null) return;
 
         // Grab counts collected from subdirectories
         self.dir.entry.pack.blocks +|= self.blocks;
@@ -334,7 +340,6 @@ const MemDir = struct {
             }
             if (self.suberr or self.dir.pack.suberr or self.dir.pack.err) p.suberr = true;
         }
-        self.entries.deinit();
     }
 };
 
@@ -473,6 +478,7 @@ pub const state = struct {
     pub var status: enum { done, err, zeroing, hlcnt, running } = .running;
     pub var threads: []Thread = undefined;
     pub var out: Out = .{ .mem = null };
+    pub var defer_json: ?*JsonWriter = null;
 
     pub var last_error: ?[:0]u8 = null;
     var last_error_lock = std.Thread.Mutex{};
@@ -492,7 +498,16 @@ pub fn setupJsonOutput(out: std.fs.File) void {
 
 // Must be the first thing to call from a source; initializes global state.
 pub fn createThreads(num: usize) []Thread {
-    std.debug.assert(num == 1 or state.out != .json);
+    switch (state.out) {
+        .mem => {},
+        .json => |j| {
+            if (num > 1) {
+                state.out = state.Out{ .mem = null };
+                state.defer_json = j;
+            }
+        },
+    }
+
     state.status = .running;
     if (state.last_error) |p| main.allocator.free(p);
     state.last_error = null;
@@ -505,7 +520,7 @@ pub fn createThreads(num: usize) []Thread {
 // Must be the last thing to call from a source.
 pub fn done() void {
     switch (state.out) {
-        .mem => {
+        .mem => if (state.defer_json == null) {
             state.status = .hlcnt;
             main.handleEvent(false, true);
             const dir = state.out.mem orelse model.root;
@@ -524,6 +539,14 @@ pub fn done() void {
     }
     state.status = .done;
     main.allocator.free(state.threads);
+
+    // We scanned into memory, now we need to scan from memory to JSON
+    if (state.defer_json) |j| {
+        state.out = state.Out{ .json = j };
+        state.defer_json = null;
+        mem_src.run(model.root);
+    }
+
     // Clear the screen when done.
     if (main.config.scan_ui == .line) main.handleEvent(false, true);
 }