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const std = @import("std");
const syntax = @import("syntax.zig");
/// A cache hit borrows its analysis; an entry too large to retain transfers
/// ownership instead. Call deinit after consuming either result.
pub const Result = struct {
analysis: syntax.SourceAnalysis,
owned: bool = false,
pub fn deinit(result: *Result, gpa: std.mem.Allocator) void {
if (result.owned) result.analysis.deinit(gpa);
result.* = undefined;
}
};
/// Owned source snapshots keep analysis valid across filesystem changes and
/// borrowed editor buffers. Entries are ordered from least to most recent.
pub const Cache = struct {
pub const max_bytes = 64 * 1024 * 1024;
pub const max_entries = 64;
const Entry = struct {
path: []u8,
source: []u8,
analysis: syntax.SourceAnalysis,
declarations_ready: bool,
colors_ready: bool,
fn size(entry: Entry) usize {
return entry.path.len + entry.source.len + entry.analysis.colors.len +
entry.analysis.declarations.len * @sizeOf(syntax.ContextDeclaration);
}
fn deinit(entry: *Entry, gpa: std.mem.Allocator) void {
gpa.free(entry.path);
gpa.free(entry.source);
entry.analysis.deinit(gpa);
}
};
entries: [max_entries]Entry = undefined,
len: usize = 0,
bytes: usize = 0,
analyses: usize = 0,
hits: usize = 0,
pub fn deinit(cache: *Cache, gpa: std.mem.Allocator) void {
for (cache.entries[0..cache.len]) |*entry| entry.deinit(gpa);
cache.* = .{};
}
/// Borrowed slices remain valid until the next get or cache deinit; an
/// owned result remains valid until Result.deinit. All calls for this
/// cache must use the same allocator. Unsupported languages
/// are cached too, including their empty analysis arrays.
pub fn get(cache: *Cache, gpa: std.mem.Allocator, path: []const u8, source: []const u8, want_declarations: bool, want_colors: bool) !Result {
return cache.getBounded(gpa, path, source, want_declarations, want_colors, max_bytes);
}
fn getBounded(cache: *Cache, gpa: std.mem.Allocator, path: []const u8, source: []const u8, want_declarations: bool, want_colors: bool, budget: usize) !Result {
if (source.len > budget or path.len > budget - source.len) return error.SourceTooLarge;
var previous: ?usize = null;
var declarations = want_declarations;
var colors = want_colors;
for (cache.entries[0..cache.len], 0..) |entry, index| {
if (!std.mem.eql(u8, entry.path, path)) continue;
previous = index;
if (!std.mem.eql(u8, entry.source, source)) break;
if ((!want_declarations or entry.declarations_ready) and (!want_colors or entry.colors_ready)) {
// Moving the small ownership record keeps the underlying
// allocations intact and avoids timestamp/overflow state.
std.mem.copyForwards(Entry, cache.entries[index .. cache.len - 1], cache.entries[index + 1 .. cache.len]);
cache.entries[cache.len - 1] = entry;
cache.hits +|= 1;
return .{ .analysis = entry.analysis };
}
declarations = declarations or entry.declarations_ready;
colors = colors or entry.colors_ready;
break;
}
// A supported full-source color map needs one byte per source byte.
// Reject that known minimum before parsing, so the caller's uncached
// path does not repeat an expensive analysis for oversized inputs.
const input_bytes = path.len + source.len;
if (colors and syntax.supportsPath(path) and source.len > budget - input_bytes) return error.SourceTooLarge;
var analysis = try syntax.analyzeSource(gpa, path, source, declarations, colors);
errdefer analysis.deinit(gpa);
cache.analyses +|= 1;
const analysis_bytes = analysis.colors.len + analysis.declarations.len * @sizeOf(syntax.ContextDeclaration);
if (analysis_bytes > budget - input_bytes) return .{ .analysis = analysis, .owned = true };
const owned_path = try gpa.dupe(u8, path);
errdefer gpa.free(owned_path);
const owned_source = try gpa.dupe(u8, source);
errdefer gpa.free(owned_source);
const next: Entry = .{
.path = owned_path,
.source = owned_source,
.analysis = analysis,
.declarations_ready = declarations,
.colors_ready = colors,
};
// Commit only after every allocation succeeds. A failed refresh leaves
// the previous cached snapshot usable by the next request.
if (previous) |index| cache.remove(gpa, index);
while (cache.len == max_entries or cache.bytes > budget - next.size()) cache.remove(gpa, 0);
cache.entries[cache.len] = next;
cache.len += 1;
cache.bytes += next.size();
return .{ .analysis = next.analysis };
}
fn remove(cache: *Cache, gpa: std.mem.Allocator, index: usize) void {
cache.bytes -= cache.entries[index].size();
cache.entries[index].deinit(gpa);
std.mem.copyForwards(Entry, cache.entries[index .. cache.len - 1], cache.entries[index + 1 .. cache.len]);
cache.len -= 1;
}
};
test "locations cache validates exact source and path and upgrades analysis" {
const gpa = std.testing.allocator;
syntax.start(gpa);
defer syntax.stop();
var cache: Cache = .{};
defer cache.deinit(gpa);
const source = "const Thing = struct {\n value: u32,\n};\n";
_ = try cache.get(gpa, "a.zig", source, true, false);
try std.testing.expectEqual(@as(usize, 1), cache.analyses);
_ = try cache.get(gpa, "a.zig", source, true, false);
try std.testing.expectEqual(@as(usize, 1), cache.analyses);
try std.testing.expectEqual(@as(usize, 1), cache.hits);
_ = try cache.get(gpa, "a.zig", source, false, true);
try std.testing.expectEqual(@as(usize, 2), cache.analyses);
try std.testing.expect(cache.entries[0].declarations_ready and cache.entries[0].colors_ready);
_ = try cache.get(gpa, "a.zig", source, true, true);
try std.testing.expectEqual(@as(usize, 2), cache.analyses);
_ = try cache.get(gpa, "a.zig", "const Thing = struct {\n other: u32,\n};\n", true, true);
try std.testing.expectEqual(@as(usize, 3), cache.analyses);
try std.testing.expectEqual(@as(usize, 1), cache.len);
_ = try cache.get(gpa, "a.txt", source, true, true);
try std.testing.expectEqual(@as(usize, 4), cache.analyses);
try std.testing.expectEqual(@as(usize, 2), cache.len);
}
test "locations cache bounds memory and entries and evicts least recently used" {
const gpa = std.testing.allocator;
var cache: Cache = .{};
defer cache.deinit(gpa);
for (0..Cache.max_entries) |index| {
var path: [32]u8 = undefined;
_ = try cache.get(gpa, try std.fmt.bufPrint(&path, "{d}.unknown", .{index}), "source", false, false);
}
_ = try cache.get(gpa, "0.unknown", "source", false, false);
_ = try cache.get(gpa, "new.unknown", "source", false, false);
try std.testing.expectEqual(Cache.max_entries, cache.len);
try std.testing.expectEqualStrings("2.unknown", cache.entries[0].path);
const count = cache.analyses;
_ = try cache.get(gpa, "0.unknown", "source", false, false);
try std.testing.expectEqual(count, cache.analyses);
cache.deinit(gpa);
_ = try cache.getBounded(gpa, "a.unknown", "source", false, false, 40);
_ = try cache.getBounded(gpa, "b.unknown", "source", false, false, 40);
_ = try cache.getBounded(gpa, "c.unknown", "source", false, false, 40);
try std.testing.expectEqual(@as(usize, 2), cache.len);
try std.testing.expect(cache.bytes <= 40);
try std.testing.expectEqualStrings("b.unknown", cache.entries[0].path);
try std.testing.expectError(error.SourceTooLarge, cache.getBounded(gpa, "large.unknown", "x" ** 41, false, false, 40));
try std.testing.expectEqual(@as(usize, 2), cache.len);
if (syntax.supportsPath("large.zig")) {
const before = cache.analyses;
try std.testing.expectError(error.SourceTooLarge, cache.getBounded(gpa, "large.zig", "x" ** 25, true, true, 40));
try std.testing.expectEqual(before, cache.analyses);
}
cache.deinit(gpa);
try std.testing.expectEqual(@as(usize, 0), cache.bytes);
try std.testing.expectEqual(@as(usize, 0), cache.len);
}
test "locations cache keeps its previous snapshot after allocation failure" {
var failing = std.testing.FailingAllocator.init(std.testing.allocator, .{});
const gpa = failing.allocator();
var cache: Cache = .{};
defer cache.deinit(gpa);
_ = try cache.get(gpa, "a.unknown", "old bytes", false, false);
const retained = cache.bytes;
failing.fail_index = failing.alloc_index;
try std.testing.expectError(error.OutOfMemory, cache.get(gpa, "a.unknown", "new bytes", false, false));
try std.testing.expectEqual(@as(usize, 1), cache.len);
try std.testing.expectEqual(retained, cache.bytes);
try std.testing.expectEqualStrings("old bytes", cache.entries[0].source);
// This succeeds with allocations still disabled because the old entry
// remains valid and the hit path moves ownership records only.
_ = try cache.get(gpa, "a.unknown", "old bytes", false, false);
try std.testing.expectEqual(@as(usize, 1), cache.hits);
}
test "locations cache transfers oversized completed analysis without reparsing" {
if (!syntax.supportsPath("large.zig")) return error.SkipZigTest;
const gpa = std.testing.allocator;
syntax.start(gpa);
defer syntax.stop();
var cache: Cache = .{};
defer cache.deinit(gpa);
const source = "const Thing = struct {\n value: u32,\n};\n";
const budget = "large.zig".len + source.len;
var result = try cache.getBounded(gpa, "large.zig", source, true, false, budget);
defer result.deinit(gpa);
try std.testing.expect(result.owned);
try std.testing.expect(result.analysis.declarations.len > 0);
try std.testing.expectEqual(@as(usize, 1), cache.analyses);
try std.testing.expectEqual(@as(usize, 0), cache.len);
try std.testing.expectEqual(@as(usize, 0), cache.bytes);
}
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