use json for fs cache metadata file

src/network/cache/FsCache.zig

@@ -22,10 +22,53 @@ const Http = @import("../http.zig");
 const CachedMetadata = Cache.CachedMetadata;
 const CachedResponse = Cache.CachedResponse;
 
+const CACHE_VERSION: usize = 1;
+
 pub const FsCache = @This();
 
 dir: std.fs.Dir,
 
+const CacheMetadataFile = struct {
+    version: usize,
+    metadata: CachedMetadata,
+};
+
+const HASHED_KEY_LEN = 64;
+const HASHED_PATH_LEN = HASHED_KEY_LEN + 5;
+const HASHED_TMP_PATH_LEN = HASHED_PATH_LEN + 4;
+
+fn hashKey(key: []const u8) [HASHED_KEY_LEN]u8 {
+    var digest: [std.crypto.hash.sha2.Sha256.digest_length]u8 = undefined;
+    std.crypto.hash.sha2.Sha256.hash(key, &digest, .{});
+    var hex: [HASHED_KEY_LEN]u8 = undefined;
+    _ = std.fmt.bufPrint(&hex, "{s}", .{std.fmt.bytesToHex(&digest, .lower)}) catch unreachable;
+    return hex;
+}
+
+fn metaPath(hashed_key: *const [HASHED_KEY_LEN]u8) [HASHED_PATH_LEN]u8 {
+    var path: [HASHED_PATH_LEN]u8 = undefined;
+    _ = std.fmt.bufPrint(&path, "{s}.meta", .{hashed_key}) catch unreachable;
+    return path;
+}
+
+fn bodyPath(hashed_key: *const [HASHED_KEY_LEN]u8) [HASHED_PATH_LEN]u8 {
+    var path: [HASHED_PATH_LEN]u8 = undefined;
+    _ = std.fmt.bufPrint(&path, "{s}.body", .{hashed_key}) catch unreachable;
+    return path;
+}
+
+fn metaTmpPath(hashed_key: *const [HASHED_KEY_LEN]u8) [HASHED_TMP_PATH_LEN]u8 {
+    var path: [HASHED_TMP_PATH_LEN]u8 = undefined;
+    _ = std.fmt.bufPrint(&path, "{s}.meta.tmp", .{hashed_key}) catch unreachable;
+    return path;
+}
+
+fn bodyTmpPath(hashed_key: *const [HASHED_KEY_LEN]u8) [HASHED_TMP_PATH_LEN]u8 {
+    var path: [HASHED_TMP_PATH_LEN]u8 = undefined;
+    _ = std.fmt.bufPrint(&path, "{s}.body.tmp", .{hashed_key}) catch unreachable;
+    return path;
+}
+
 pub fn init(path: []const u8) !FsCache {
     const cwd = std.fs.cwd();
 
@@ -46,257 +89,86 @@ pub fn cache(self: *FsCache) Cache {
     return Cache.init(self);
 }
 
-const HASHED_KEY_LEN = 64;
-const HASHED_PATH_LEN = HASHED_KEY_LEN + 5;
-const HASHED_TMP_PATH_LEN = HASHED_PATH_LEN + 4;
-
-fn hashKey(key: []const u8) [HASHED_KEY_LEN]u8 {
-    var digest: [std.crypto.hash.sha2.Sha256.digest_length]u8 = undefined;
-    std.crypto.hash.sha2.Sha256.hash(key, &digest, .{});
-    var hex: [HASHED_KEY_LEN]u8 = undefined;
-    _ = std.fmt.bufPrint(&hex, "{s}", .{std.fmt.bytesToHex(&digest, .lower)}) catch unreachable;
-    return hex;
-}
-
-fn serializeMeta(writer: *std.Io.Writer, meta: *const CachedMetadata) !void {
-    try writer.print("{s}\n{s}\n", .{ meta.url, meta.content_type });
-    try writer.print("{d}\n{d}\n{d}\n", .{
-        meta.status,
-        meta.stored_at,
-        meta.age_at_store,
-    });
-    try writer.print("{s}\n", .{meta.etag orelse "null"});
-    try writer.print("{s}\n", .{meta.last_modified orelse "null"});
-
-    // cache-control
-    try writer.print("{d}\n", .{meta.cache_control.max_age orelse 0});
-    try writer.print("{}\n{}\n{}\n{}\n", .{
-        meta.cache_control.max_age != null,
-        meta.cache_control.must_revalidate,
-        meta.cache_control.no_cache,
-        meta.cache_control.immutable,
-    });
-
-    // vary
-    if (meta.vary) |v| {
-        try writer.print("{s}\n", .{v.toString()});
-    } else {
-        try writer.print("null\n", .{});
-    }
-    try writer.flush();
-
-    try writer.print("{d}\n", .{meta.headers.len});
-    for (meta.headers) |hdr| {
-        try writer.print("{s}\n{s}\n", .{ hdr.name, hdr.value });
-        try writer.flush();
-    }
-    try writer.flush();
-}
-
-fn deserializeMetaOptionalString(bytes: []const u8) ?[]const u8 {
-    if (std.mem.eql(u8, bytes, "null")) return null else return bytes;
-}
-
-fn deserializeMetaBoolean(bytes: []const u8) !bool {
-    if (std.mem.eql(u8, bytes, "true")) return true;
-    if (std.mem.eql(u8, bytes, "false")) return false;
-    return error.Malformed;
-}
-
-fn deserializeMeta(allocator: std.mem.Allocator, file: std.fs.File) !CachedMetadata {
-    var file_buf: [1024]u8 = undefined;
-    var file_reader = file.reader(&file_buf);
-    const reader = &file_reader.interface;
-
-    const url = blk: {
-        const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-        break :blk try allocator.dupeZ(u8, line);
-    };
-    errdefer allocator.free(url);
-
-    const content_type = blk: {
-        const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-        break :blk try allocator.dupe(u8, line);
-    };
-    errdefer allocator.free(content_type);
-
-    const status = blk: {
-        const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-        break :blk std.fmt.parseInt(u16, line, 10) catch return error.Malformed;
-    };
-    const stored_at = blk: {
-        const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-        break :blk std.fmt.parseInt(i64, line, 10) catch return error.Malformed;
-    };
-    const age_at_store = blk: {
-        const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-        break :blk std.fmt.parseInt(u64, line, 10) catch return error.Malformed;
-    };
-
-    const etag = blk: {
-        const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-        break :blk if (std.mem.eql(u8, line, "null")) null else try allocator.dupe(u8, line);
-    };
-    errdefer if (etag) |e| allocator.free(e);
-
-    const last_modified = blk: {
-        const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-        break :blk if (std.mem.eql(u8, line, "null")) null else try allocator.dupe(u8, line);
-    };
-    errdefer if (last_modified) |lm| allocator.free(lm);
-
-    // cache-control
-    const cc = cache_control: {
-        const max_age_val = blk: {
-            const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-            break :blk std.fmt.parseInt(u64, line, 10) catch return error.Malformed;
-        };
-        const max_age_present = blk: {
-            const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-            break :blk try deserializeMetaBoolean(line);
-        };
-        const must_revalidate = blk: {
-            const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-            break :blk try deserializeMetaBoolean(line);
-        };
-        const no_cache = blk: {
-            const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-            break :blk try deserializeMetaBoolean(line);
-        };
-        const immutable = blk: {
-            const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-            break :blk try deserializeMetaBoolean(line);
-        };
-        break :cache_control Cache.CacheControl{
-            .max_age = if (max_age_present) max_age_val else null,
-            .must_revalidate = must_revalidate,
-            .no_cache = no_cache,
-            .immutable = immutable,
-        };
-    };
-
-    // vary
-    const vary = blk: {
-        const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-        if (std.mem.eql(u8, line, "null")) break :blk null;
-        const duped = try allocator.dupe(u8, line);
-        break :blk Cache.Vary.parse(duped);
-    };
-    errdefer if (vary) |v| if (v == .value) allocator.free(v.value);
-
-    const headers = blk: {
-        const line = try reader.takeDelimiter('\n') orelse return error.Malformed;
-        const count = std.fmt.parseInt(usize, line, 10) catch return error.Malformed;
-
-        const hdrs = try allocator.alloc(Http.Header, count);
-        errdefer allocator.free(hdrs);
-
-        for (hdrs) |*hdr| {
-            const name = try reader.takeDelimiter('\n') orelse return error.Malformed;
-            const value = try reader.takeDelimiter('\n') orelse return error.Malformed;
-            hdr.* = .{
-                .name = try allocator.dupe(u8, name),
-                .value = try allocator.dupe(u8, value),
-            };
-        }
-
-        break :blk hdrs;
-    };
-    errdefer {
-        for (headers) |hdr| {
-            allocator.free(hdr.name);
-            allocator.free(hdr.value);
-        }
-        allocator.free(headers);
-    }
-
-    return .{
-        .url = url,
-        .content_type = content_type,
-        .status = status,
-        .stored_at = stored_at,
-        .age_at_store = age_at_store,
-        .cache_control = cc,
-        .etag = etag,
-        .last_modified = last_modified,
-        .vary = vary,
-        .headers = headers,
-    };
-}
-
-pub fn get(self: *FsCache, allocator: std.mem.Allocator, key: []const u8) ?Cache.CachedResponse {
+pub fn get(self: *FsCache, arena: std.mem.Allocator, key: []const u8) ?Cache.CachedResponse {
     const hashed_key = hashKey(key);
+    const meta_p = metaPath(&hashed_key);
+    const body_p = bodyPath(&hashed_key);
 
-    var meta_path: [HASHED_PATH_LEN]u8 = undefined;
-    _ = std.fmt.bufPrint(&meta_path, "{s}.meta", .{hashed_key}) catch @panic("FsCache.get meta path overflowed");
-
-    var body_path: [HASHED_PATH_LEN]u8 = undefined;
-    _ = std.fmt.bufPrint(&body_path, "{s}.body", .{hashed_key}) catch @panic("FsCache.get body path overflowed");
-
-    const meta_file = self.dir.openFile(&meta_path, .{ .mode = .read_only }) catch return null;
+    const meta_file = self.dir.openFile(&meta_p, .{ .mode = .read_only }) catch return null;
     defer meta_file.close();
 
-    const meta = deserializeMeta(allocator, meta_file) catch {
-        self.dir.deleteFile(&meta_path) catch {};
-        self.dir.deleteFile(&body_path) catch {};
+    const contents = meta_file.readToEndAlloc(arena, 1 * 1024 * 1024) catch return null;
+    defer arena.free(contents);
+
+    const cache_file: CacheMetadataFile = std.json.parseFromSliceLeaky(
+        CacheMetadataFile,
+        arena,
+        contents,
+        .{ .allocate = .alloc_always },
+    ) catch {
+        self.dir.deleteFile(&meta_p) catch {};
+        self.dir.deleteFile(&body_p) catch {};
         return null;
     };
 
-    const body_file = self.dir.openFile(&body_path, .{ .mode = .read_only }) catch return null;
+    const metadata = cache_file.metadata;
+
+    if (cache_file.version != CACHE_VERSION) {
+        self.dir.deleteFile(&meta_p) catch {};
+        self.dir.deleteFile(&body_p) catch {};
+        return null;
+    }
+
+    const body_file = self.dir.openFile(
+        &body_p,
+        .{ .mode = .read_only },
+    ) catch return null;
 
     return .{
-        .metadata = meta,
+        .metadata = metadata,
         .data = .{ .file = body_file },
     };
 }
 
 pub fn put(self: *FsCache, key: []const u8, meta: CachedMetadata, body: []const u8) !void {
     const hashed_key = hashKey(key);
-
-    // Write meta to a temp file, then atomically rename into place
-    var meta_path: [HASHED_PATH_LEN]u8 = undefined;
-    _ = std.fmt.bufPrint(&meta_path, "{s}.meta", .{hashed_key}) catch
-        @panic("FsCache.put meta path overflowed");
-
-    var meta_tmp_path: [HASHED_TMP_PATH_LEN]u8 = undefined;
-    _ = std.fmt.bufPrint(&meta_tmp_path, "{s}.meta.tmp", .{hashed_key}) catch
-        @panic("FsCache.put meta tmp path overflowed");
+    const meta_p = metaPath(&hashed_key);
+    const meta_tmp_p = metaTmpPath(&hashed_key);
+    const body_p = bodyPath(&hashed_key);
+    const body_tmp_p = bodyTmpPath(&hashed_key);
 
     {
-        const meta_file = try self.dir.createFile(&meta_tmp_path, .{});
+        const meta_file = try self.dir.createFile(&meta_tmp_p, .{});
         errdefer {
             meta_file.close();
-            self.dir.deleteFile(&meta_tmp_path) catch {};
+            self.dir.deleteFile(&meta_tmp_p) catch {};
         }
 
-        var buf: [512]u8 = undefined;
-        var meta_file_writer = meta_file.writer(&buf);
-        try serializeMeta(&meta_file_writer.interface, &meta);
+        var meta_file_writer_buf: [512]u8 = undefined;
+        var meta_file_writer = meta_file.writer(&meta_file_writer_buf);
+        const meta_file_writer_iface = &meta_file_writer.interface;
+        try std.json.Stringify.value(
+            CacheMetadataFile{ .version = CACHE_VERSION, .metadata = meta },
+            .{ .whitespace = .minified },
+            meta_file_writer_iface,
+        );
+        try meta_file_writer_iface.flush();
         meta_file.close();
     }
-    errdefer self.dir.deleteFile(&meta_tmp_path) catch {};
-    try self.dir.rename(&meta_tmp_path, &meta_path);
-
-    // Write body to a temp file, then atomically rename into place
-    var body_path: [HASHED_PATH_LEN]u8 = undefined;
-    _ = std.fmt.bufPrint(&body_path, "{s}.body", .{hashed_key}) catch
-        @panic("FsCache.put body path overflowed");
-
-    var body_tmp_path: [HASHED_TMP_PATH_LEN]u8 = undefined;
-    _ = std.fmt.bufPrint(&body_tmp_path, "{s}.body.tmp", .{hashed_key}) catch
-        @panic("FsCache.put body tmp path overflowed");
+    errdefer self.dir.deleteFile(&meta_tmp_p) catch {};
+    try self.dir.rename(&meta_tmp_p, &meta_p);
 
     {
-        const body_file = try self.dir.createFile(&body_tmp_path, .{});
+        const body_file = try self.dir.createFile(&body_tmp_p, .{});
         errdefer {
             body_file.close();
-            self.dir.deleteFile(&body_tmp_path) catch {};
+            self.dir.deleteFile(&body_tmp_p) catch {};
         }
         try body_file.writeAll(body);
         body_file.close();
     }
-    errdefer self.dir.deleteFile(&body_tmp_path) catch {};
+    errdefer self.dir.deleteFile(&body_tmp_p) catch {};
 
-    errdefer self.dir.deleteFile(&meta_path) catch {};
-    try self.dir.rename(&body_tmp_path, &body_path);
+    errdefer self.dir.deleteFile(&meta_p) catch {};
+    try self.dir.rename(&body_tmp_p, &body_p);
 }