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Cache Revalidation

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This commit is contained in:
Muki Kiboigo
2026-05-28 08:47:48 -07:00
parent a6c8a28977
commit feefcd4650
2 changed files with 97 additions and 19 deletions
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24
src/network/cache/Cache.zig vendored
View File

@@ -69,6 +69,7 @@ pub fn clear(self: *Cache) !void {
pub const CacheControl = struct {
max_age: u64,
must_revalidate: bool = false,
pub fn parse(value: []const u8) ?CacheControl {
var cc: CacheControl = .{ .max_age = undefined };
@@ -88,7 +89,8 @@ pub const CacheControl = struct {
return null;
}
if (std.mem.eql(u8, directive, "no-cache")) {
return null;
cc.must_revalidate = true;
continue;
}
if (std.mem.eql(u8, directive, "private")) {
return null;
@@ -132,15 +134,17 @@ pub const CachedMetadata = struct {
vary_headers: []const Http.Header,
// Validators for conditional requests.
etag: ?[]const u8 = null,
last_modified: ?[]const u8 = null,
etag: ?[]const u8,
last_modified: ?[]const u8,
pub fn format(self: CachedMetadata, writer: *std.Io.Writer) !void {
try writer.print("url={s} | status={d} | content_type={s} | max_age={d} | vary=[", .{
try writer.print("url={s} | status={d} | content_type={s} | max_age={d} | etag={s} | last-modified={s} | vary=[", .{
self.url,
self.status,
self.content_type,
self.cache_control.max_age,
self.etag orelse "null",
self.last_modified orelse "null",
});
// Logging all headers gets pretty verbose...
@@ -156,6 +160,7 @@ pub const CachedMetadata = struct {
}
pub fn isStale(self: CachedMetadata, timestamp: i64) bool {
if (self.cache_control.must_revalidate) return true;
const age = (timestamp - self.stored_at) + @as(i64, @intCast(self.age_at_store));
return age >= @as(i64, @intCast(self.cache_control.max_age));
}
@@ -179,6 +184,13 @@ pub const CachedData = union(enum) {
len: usize,
},
pub fn deinit(self: CachedData) void {
switch (self) {
.buffer => {},
.file => |*f| f.file.close(),
}
}
pub fn format(self: CachedData, writer: *std.Io.Writer) !void {
switch (self) {
.buffer => |buf| try writer.print("buffer({d} bytes)", .{buf.len}),
@@ -210,6 +222,8 @@ pub fn tryCache(
cache_control: ?[]const u8,
vary: ?[]const u8,
age: ?[]const u8,
etag: ?[]const u8,
last_modified: ?[]const u8,
has_set_cookie: bool,
has_authorization: bool,
) !?CachedMetadata {
@@ -250,6 +264,8 @@ pub fn tryCache(
.cache_control = cc,
.headers = &.{},
.vary_headers = &.{},
.etag = if (etag) |e| try arena.dupe(u8, e) else null,
.last_modified = if (last_modified) |lm| try arena.dupe(u8, lm) else null,
};
}
const testing = @import("../../testing.zig");

92
src/network/layer/CacheLayer.zig
View File

@@ -66,8 +66,23 @@ fn request(ptr: *anyopaque, transfer: *Transfer) anyerror!void {
.request_headers = req_header_list.items,
})) |cached| {
if (cached.expired) {
// If it is expired, evict from Cache.
transfer.client.network.cache.?.evict(req.url);
if (cached.metadata.hasValidators()) {
if (cached.metadata.etag) |etag| {
log.debug(.cache, "revalidate with etag", .{ .url = req.url, .etag = etag });
const header_value = try std.fmt.allocPrintSentinel(arena, "If-None-Match: {s}", .{etag}, 0);
try req.headers.add(header_value.ptr);
} else if (cached.metadata.last_modified) |lm| {
log.debug(.cache, "revalidate with last-modified", .{ .url = req.url, .last_modified = lm });
const header_value = try std.fmt.allocPrintSentinel(arena, "If-Modified-Since: {s}", .{lm}, 0);
try req.headers.add(header_value.ptr);
}
try installCacheContext(arena, transfer, cached);
return self.next.request(transfer);
} else {
// If it is expired, evict from Cache.
transfer.client.network.cache.?.evict(req.url);
}
} else {
// Dispatch that the Request was served from the Cache.
transfer.req.notification.dispatch(
@@ -105,6 +120,16 @@ fn request(ptr: *anyopaque, transfer: *Transfer) anyerror!void {
// Cache miss: install wrappers so we can inspect the response and decide
// whether to write the body into the cache when it's done.
try installCacheContext(arena, transfer, null);
return self.next.request(transfer);
}
fn installCacheContext(
arena: std.mem.Allocator,
transfer: *Transfer,
stale_entry: ?CachedResponse,
) !void {
const req = &transfer.req;
const ctx = try arena.create(CacheContext);
ctx.* = .{
.arena = arena,
@@ -112,6 +137,7 @@ fn request(ptr: *anyopaque, transfer: *Transfer) anyerror!void {
.forward = Forward.capture(req),
.req_url = req.url,
.req_headers = req.headers,
.stale_entry = stale_entry,
};
req.ctx = ctx;
@@ -120,16 +146,8 @@ fn request(ptr: *anyopaque, transfer: *Transfer) anyerror!void {
req.done_callback = CacheContext.doneCallback;
req.error_callback = CacheContext.errorCallback;
if (ctx.forward.start != null) {
// req.ctx was changed, need to ovewrite this
req.start_callback = CacheContext.startCallback;
}
if (ctx.forward.shutdown != null) {
// req.ctx was changed, need to ovewrite this
req.shutdown_callback = CacheContext.shutdownCallback;
}
return self.next.request(transfer);
if (ctx.forward.start != null) req.start_callback = CacheContext.startCallback;
if (ctx.forward.shutdown != null) req.shutdown_callback = CacheContext.shutdownCallback;
}
fn serveFromCache(req: *Request, cached: *const CachedResponse) !void {
@@ -182,6 +200,7 @@ const CacheContext = struct {
req_url: [:0]const u8,
req_headers: @import("../http.zig").Headers,
pending_metadata: ?*CachedMetadata = null,
stale_entry: ?CachedResponse = null,
fn startCallback(response: Response) anyerror!void {
const self: *CacheContext = @ptrCast(@alignCast(response.ctx));
@@ -195,6 +214,12 @@ const CacheContext = struct {
fn headerCallback(response: Response) anyerror!bool {
const self: *CacheContext = @ptrCast(@alignCast(response.ctx));
defer {
if (self.stale_entry) |stale| {
stale.data.deinit();
}
self.stale_entry = null;
}
// For non-transfer responses (fulfilled by interception, or future
// cached-while-cached cases), there's nothing to inspect for caching
@@ -205,11 +230,46 @@ const CacheContext = struct {
};
const arena = self.arena;
const conn = transfer._conn.?;
const vary = if (conn.getResponseHeader("vary", 0)) |h| h.value else null;
var rh = &transfer.res.header.?;
if (self.stale_entry != null and rh.status == 304) {
const stale = self.stale_entry.?;
self.stale_entry = null;
transfer.client.network.cache.?.revalidate(
arena,
self.req_url,
std.time.timestamp(),
) catch |err| {
log.warn(.cache, "revalidate failed", .{ .err = err });
};
const ctx = try arena.create(CachedResponse);
ctx.* = stale;
try transfer.client.runNextTick(transfer, ctx, .{
.run = struct {
fn run(t: *Transfer, ctx_ptr: *anyopaque) void {
defer t.deinit();
const c: *CachedResponse = @ptrCast(@alignCast(ctx_ptr));
serveFromCache(&t.req, c) catch |err| {
t.req.error_callback(t.req.ctx, err);
};
}
}.run,
.abort = struct {
fn abort(ctx_ptr: *anyopaque) void {
const c: *CachedResponse = @ptrCast(@alignCast(ctx_ptr));
c.data.deinit();
}
}.abort,
});
return false;
}
const vary = if (conn.getResponseHeader("vary", 0)) |h| h.value else null;
const maybe_cm = try Cache.tryCache(
arena,
std.time.timestamp(),
@@ -219,6 +279,8 @@ const CacheContext = struct {
if (conn.getResponseHeader("cache-control", 0)) |h| h.value else null,
vary,
if (conn.getResponseHeader("age", 0)) |h| h.value else null,
if (conn.getResponseHeader("etag", 0)) |h| h.value else null,
if (conn.getResponseHeader("last-modified", 0)) |h| h.value else null,
conn.getResponseHeader("set-cookie", 0) != null,
conn.getResponseHeader("authorization", 0) != null,
);