create Cache interface file

src/network/cache/Cache.zig

@@ -0,0 +1,97 @@
+// Copyright (C) 2023-2026  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+
+/// A browser-wide cache for resources across the network.
+/// This mostly conforms to RFC9111 with regards to caching behavior.
+pub const Cache = @This();
+
+ptr: *anyopaque,
+vtable: *const VTable,
+
+const VTable = struct {
+    get: *const fn (ptr: *anyopaque, allocator: std.mem.Allocator, key: []const u8) ?CachedResponse,
+    put: *const fn (ptr: *anyopaque, key: []const u8, metadata: CachedMetadata, body: []const u8) anyerror!void,
+};
+
+pub fn init(ptr: anytype) Cache {
+    const T = @TypeOf(ptr.*);
+
+    return .{
+        .ptr = ptr,
+        .vtable = &.{
+            .get = T.get,
+            .put = T.put,
+        },
+    };
+}
+
+pub fn get(self: Cache, allocator: std.mem.Allocator, key: []const u8) ?CachedResponse {
+    return self.vtable.get(self.ptr, allocator, key);
+}
+
+pub fn put(self: Cache, key: []const u8, metadata: CachedMetadata, body: []const u8) !void {
+    return self.vtable.put(self.ptr, key, metadata, body);
+}
+
+pub const CachedMetadata = struct {
+    url: [:0]const u8,
+    content_type: []const u8,
+
+    status: u16,
+    stored_at: i64,
+    age_at_store: u64,
+    max_age: u64,
+
+    // for If-None-Match
+    etag: ?[]const u8,
+    // for If-Modified-Since
+    last_modified: ?[]const u8,
+
+    must_revalidate: bool,
+    no_cache: bool,
+    immutable: bool,
+
+    // If non-null, must be incorporated into cache key.
+    vary: ?[]const u8,
+
+    pub fn deinit(self: CachedMetadata, allocator: std.mem.Allocator) void {
+        allocator.free(self.url);
+        allocator.free(self.content_type);
+        if (self.etag) |e| allocator.free(e);
+        if (self.last_modified) |lm| allocator.free(lm);
+        if (self.vary) |v| allocator.free(v);
+    }
+
+    pub fn isAgeStale(self: *const CachedMetadata) bool {
+        const now = std.time.timestamp();
+        const age = now - self.stored_at + @as(i64, @intCast(self.age_at_store));
+        return age < @as(i64, @intCast(self.max_age));
+    }
+};
+
+pub const CachedData = union(enum) {
+    buffer: []const u8,
+    file: std.fs.File,
+};
+
+pub const CachedResponse = struct {
+    metadata: CachedMetadata,
+    data: CachedData,
+};