zig/lib/std/Build/Cache.zig
Andrew Kelley 5a34e6c3e6 frontend: add file system inputs for incremental cache mode
These are also used for whole cache mode in the case that any compile
errors are emitted.
2024-07-12 00:15:11 -07:00

1362 lines
48 KiB
Zig

//! Manages `zig-cache` directories.
//! This is not a general-purpose cache. It is designed to be fast and simple,
//! not to withstand attacks using specially-crafted input.
gpa: Allocator,
manifest_dir: fs.Dir,
hash: HashHelper = .{},
/// This value is accessed from multiple threads, protected by mutex.
recent_problematic_timestamp: i128 = 0,
mutex: std.Thread.Mutex = .{},
/// A set of strings such as the zig library directory or project source root, which
/// are stripped from the file paths before putting into the cache. They
/// are replaced with single-character indicators. This is not to save
/// space but to eliminate absolute file paths. This improves portability
/// and usefulness of the cache for advanced use cases.
prefixes_buffer: [4]Directory = undefined,
prefixes_len: usize = 0,
pub const Path = @import("Cache/Path.zig");
pub const Directory = @import("Cache/Directory.zig");
pub const DepTokenizer = @import("Cache/DepTokenizer.zig");
const Cache = @This();
const std = @import("std");
const builtin = @import("builtin");
const crypto = std.crypto;
const fs = std.fs;
const assert = std.debug.assert;
const testing = std.testing;
const mem = std.mem;
const fmt = std.fmt;
const Allocator = std.mem.Allocator;
const log = std.log.scoped(.cache);
pub fn addPrefix(cache: *Cache, directory: Directory) void {
cache.prefixes_buffer[cache.prefixes_len] = directory;
cache.prefixes_len += 1;
}
/// Be sure to call `Manifest.deinit` after successful initialization.
pub fn obtain(cache: *Cache) Manifest {
return Manifest{
.cache = cache,
.hash = cache.hash,
.manifest_file = null,
.manifest_dirty = false,
.hex_digest = undefined,
};
}
pub fn prefixes(cache: *const Cache) []const Directory {
return cache.prefixes_buffer[0..cache.prefixes_len];
}
const PrefixedPath = struct {
prefix: u8,
sub_path: []const u8,
fn eql(a: PrefixedPath, b: PrefixedPath) bool {
return a.prefix == b.prefix and std.mem.eql(u8, a.sub_path, b.sub_path);
}
fn hash(pp: PrefixedPath) u32 {
return @truncate(std.hash.Wyhash.hash(pp.prefix, pp.sub_path));
}
};
fn findPrefix(cache: *const Cache, file_path: []const u8) !PrefixedPath {
const gpa = cache.gpa;
const resolved_path = try fs.path.resolve(gpa, &[_][]const u8{file_path});
errdefer gpa.free(resolved_path);
return findPrefixResolved(cache, resolved_path);
}
/// Takes ownership of `resolved_path` on success.
fn findPrefixResolved(cache: *const Cache, resolved_path: []u8) !PrefixedPath {
const gpa = cache.gpa;
const prefixes_slice = cache.prefixes();
var i: u8 = 1; // Start at 1 to skip over checking the null prefix.
while (i < prefixes_slice.len) : (i += 1) {
const p = prefixes_slice[i].path.?;
const sub_path = getPrefixSubpath(gpa, p, resolved_path) catch |err| switch (err) {
error.NotASubPath => continue,
else => |e| return e,
};
// Free the resolved path since we're not going to return it
gpa.free(resolved_path);
return PrefixedPath{
.prefix = i,
.sub_path = sub_path,
};
}
return PrefixedPath{
.prefix = 0,
.sub_path = resolved_path,
};
}
fn getPrefixSubpath(allocator: Allocator, prefix: []const u8, path: []u8) ![]u8 {
const relative = try std.fs.path.relative(allocator, prefix, path);
errdefer allocator.free(relative);
var component_iterator = std.fs.path.NativeComponentIterator.init(relative) catch {
return error.NotASubPath;
};
if (component_iterator.root() != null) {
return error.NotASubPath;
}
const first_component = component_iterator.first();
if (first_component != null and std.mem.eql(u8, first_component.?.name, "..")) {
return error.NotASubPath;
}
return relative;
}
/// This is 128 bits - Even with 2^54 cache entries, the probably of a collision would be under 10^-6
pub const bin_digest_len = 16;
pub const hex_digest_len = bin_digest_len * 2;
pub const BinDigest = [bin_digest_len]u8;
pub const HexDigest = [hex_digest_len]u8;
/// This is currently just an arbitrary non-empty string that can't match another manifest line.
const manifest_header = "0";
const manifest_file_size_max = 100 * 1024 * 1024;
/// The type used for hashing file contents. Currently, this is SipHash128(1, 3), because it
/// provides enough collision resistance for the Manifest use cases, while being one of our
/// fastest options right now.
pub const Hasher = crypto.auth.siphash.SipHash128(1, 3);
/// Initial state with random bytes, that can be copied.
/// Refresh this with new random bytes when the manifest
/// format is modified in a non-backwards-compatible way.
pub const hasher_init: Hasher = Hasher.init(&[_]u8{
0x33, 0x52, 0xa2, 0x84,
0xcf, 0x17, 0x56, 0x57,
0x01, 0xbb, 0xcd, 0xe4,
0x77, 0xd6, 0xf0, 0x60,
});
pub const File = struct {
prefixed_path: PrefixedPath,
max_file_size: ?usize,
stat: Stat,
bin_digest: BinDigest,
contents: ?[]const u8,
pub const Stat = struct {
inode: fs.File.INode,
size: u64,
mtime: i128,
};
pub fn deinit(self: *File, gpa: Allocator) void {
gpa.free(self.prefixed_path.sub_path);
if (self.contents) |contents| {
gpa.free(contents);
self.contents = null;
}
self.* = undefined;
}
pub fn updateMaxSize(file: *File, new_max_size: ?usize) void {
const new = new_max_size orelse return;
file.max_file_size = if (file.max_file_size) |old| @max(old, new) else new;
}
};
pub const HashHelper = struct {
hasher: Hasher = hasher_init,
/// Record a slice of bytes as a dependency of the process being cached.
pub fn addBytes(hh: *HashHelper, bytes: []const u8) void {
hh.hasher.update(mem.asBytes(&bytes.len));
hh.hasher.update(bytes);
}
pub fn addOptionalBytes(hh: *HashHelper, optional_bytes: ?[]const u8) void {
hh.add(optional_bytes != null);
hh.addBytes(optional_bytes orelse return);
}
pub fn addListOfBytes(hh: *HashHelper, list_of_bytes: []const []const u8) void {
hh.add(list_of_bytes.len);
for (list_of_bytes) |bytes| hh.addBytes(bytes);
}
pub fn addOptionalListOfBytes(hh: *HashHelper, optional_list_of_bytes: ?[]const []const u8) void {
hh.add(optional_list_of_bytes != null);
hh.addListOfBytes(optional_list_of_bytes orelse return);
}
/// Convert the input value into bytes and record it as a dependency of the process being cached.
pub fn add(hh: *HashHelper, x: anytype) void {
switch (@TypeOf(x)) {
std.SemanticVersion => {
hh.add(x.major);
hh.add(x.minor);
hh.add(x.patch);
},
std.Target.Os.TaggedVersionRange => {
switch (x) {
.linux => |linux| {
hh.add(linux.range.min);
hh.add(linux.range.max);
hh.add(linux.glibc);
},
.windows => |windows| {
hh.add(windows.min);
hh.add(windows.max);
},
.semver => |semver| {
hh.add(semver.min);
hh.add(semver.max);
},
.none => {},
}
},
std.zig.BuildId => switch (x) {
.none, .fast, .uuid, .sha1, .md5 => hh.add(std.meta.activeTag(x)),
.hexstring => |hex_string| hh.addBytes(hex_string.toSlice()),
},
else => switch (@typeInfo(@TypeOf(x))) {
.Bool, .Int, .Enum, .Array => hh.addBytes(mem.asBytes(&x)),
else => @compileError("unable to hash type " ++ @typeName(@TypeOf(x))),
},
}
}
pub fn addOptional(hh: *HashHelper, optional: anytype) void {
hh.add(optional != null);
hh.add(optional orelse return);
}
/// Returns a hex encoded hash of the inputs, without modifying state.
pub fn peek(hh: HashHelper) [hex_digest_len]u8 {
var copy = hh;
return copy.final();
}
pub fn peekBin(hh: HashHelper) BinDigest {
var copy = hh;
var bin_digest: BinDigest = undefined;
copy.hasher.final(&bin_digest);
return bin_digest;
}
/// Returns a hex encoded hash of the inputs, mutating the state of the hasher.
pub fn final(hh: *HashHelper) HexDigest {
var bin_digest: BinDigest = undefined;
hh.hasher.final(&bin_digest);
return binToHex(bin_digest);
}
pub fn oneShot(bytes: []const u8) [hex_digest_len]u8 {
var hasher: Hasher = hasher_init;
hasher.update(bytes);
var bin_digest: BinDigest = undefined;
hasher.final(&bin_digest);
return binToHex(bin_digest);
}
};
pub fn binToHex(bin_digest: BinDigest) HexDigest {
var out_digest: HexDigest = undefined;
_ = fmt.bufPrint(
&out_digest,
"{s}",
.{fmt.fmtSliceHexLower(&bin_digest)},
) catch unreachable;
return out_digest;
}
pub const Lock = struct {
manifest_file: fs.File,
pub fn release(lock: *Lock) void {
if (builtin.os.tag == .windows) {
// Windows does not guarantee that locks are immediately unlocked when
// the file handle is closed. See LockFileEx documentation.
lock.manifest_file.unlock();
}
lock.manifest_file.close();
lock.* = undefined;
}
};
pub const Manifest = struct {
cache: *Cache,
/// Current state for incremental hashing.
hash: HashHelper,
manifest_file: ?fs.File,
manifest_dirty: bool,
/// Set this flag to true before calling hit() in order to indicate that
/// upon a cache hit, the code using the cache will not modify the files
/// within the cache directory. This allows multiple processes to utilize
/// the same cache directory at the same time.
want_shared_lock: bool = true,
have_exclusive_lock: bool = false,
// Indicate that we want isProblematicTimestamp to perform a filesystem write in
// order to obtain a problematic timestamp for the next call. Calls after that
// will then use the same timestamp, to avoid unnecessary filesystem writes.
want_refresh_timestamp: bool = true,
files: Files = .{},
hex_digest: HexDigest,
/// Populated when hit() returns an error because of one
/// of the files listed in the manifest.
failed_file_index: ?usize = null,
/// Keeps track of the last time we performed a file system write to observe
/// what time the file system thinks it is, according to its own granularity.
recent_problematic_timestamp: i128 = 0,
pub const Files = std.ArrayHashMapUnmanaged(File, void, FilesContext, false);
pub const FilesContext = struct {
pub fn hash(fc: FilesContext, file: File) u32 {
_ = fc;
return file.prefixed_path.hash();
}
pub fn eql(fc: FilesContext, a: File, b: File, b_index: usize) bool {
_ = fc;
_ = b_index;
return a.prefixed_path.eql(b.prefixed_path);
}
};
const FilesAdapter = struct {
pub fn eql(context: @This(), a: PrefixedPath, b: File, b_index: usize) bool {
_ = context;
_ = b_index;
return a.eql(b.prefixed_path);
}
pub fn hash(context: @This(), key: PrefixedPath) u32 {
_ = context;
return key.hash();
}
};
/// Add a file as a dependency of process being cached. When `hit` is
/// called, the file's contents will be checked to ensure that it matches
/// the contents from previous times.
///
/// Max file size will be used to determine the amount of space the file contents
/// are allowed to take up in memory. If max_file_size is null, then the contents
/// will not be loaded into memory.
///
/// Returns the index of the entry in the `files` array list. You can use it
/// to access the contents of the file after calling `hit()` like so:
///
/// ```
/// var file_contents = cache_hash.files.keys()[file_index].contents.?;
/// ```
pub fn addFilePath(m: *Manifest, file_path: Path, max_file_size: ?usize) !usize {
const gpa = m.cache.gpa;
try m.files.ensureUnusedCapacity(gpa, 1);
const resolved_path = try fs.path.resolve(gpa, &.{
file_path.root_dir.path orelse ".",
file_path.subPathOrDot(),
});
errdefer gpa.free(resolved_path);
const prefixed_path = try m.cache.findPrefixResolved(resolved_path);
return addFileInner(m, prefixed_path, max_file_size);
}
/// Deprecated; use `addFilePath`.
pub fn addFile(self: *Manifest, file_path: []const u8, max_file_size: ?usize) !usize {
assert(self.manifest_file == null);
const gpa = self.cache.gpa;
try self.files.ensureUnusedCapacity(gpa, 1);
const prefixed_path = try self.cache.findPrefix(file_path);
errdefer gpa.free(prefixed_path.sub_path);
return addFileInner(self, prefixed_path, max_file_size);
}
fn addFileInner(self: *Manifest, prefixed_path: PrefixedPath, max_file_size: ?usize) !usize {
const gop = self.files.getOrPutAssumeCapacityAdapted(prefixed_path, FilesAdapter{});
if (gop.found_existing) {
gop.key_ptr.updateMaxSize(max_file_size);
return gop.index;
}
gop.key_ptr.* = .{
.prefixed_path = prefixed_path,
.contents = null,
.max_file_size = max_file_size,
.stat = undefined,
.bin_digest = undefined,
};
self.hash.add(prefixed_path.prefix);
self.hash.addBytes(prefixed_path.sub_path);
return gop.index;
}
pub fn addOptionalFile(self: *Manifest, optional_file_path: ?[]const u8) !void {
self.hash.add(optional_file_path != null);
const file_path = optional_file_path orelse return;
_ = try self.addFile(file_path, null);
}
pub fn addListOfFiles(self: *Manifest, list_of_files: []const []const u8) !void {
self.hash.add(list_of_files.len);
for (list_of_files) |file_path| {
_ = try self.addFile(file_path, null);
}
}
pub fn addDepFile(self: *Manifest, dir: fs.Dir, dep_file_basename: []const u8) !void {
assert(self.manifest_file == null);
return self.addDepFileMaybePost(dir, dep_file_basename);
}
/// Check the cache to see if the input exists in it. If it exists, returns `true`.
/// A hex encoding of its hash is available by calling `final`.
///
/// This function will also acquire an exclusive lock to the manifest file. This means
/// that a process holding a Manifest will block any other process attempting to
/// acquire the lock. If `want_shared_lock` is `true`, a cache hit guarantees the
/// manifest file to be locked in shared mode, and a cache miss guarantees the manifest
/// file to be locked in exclusive mode.
///
/// The lock on the manifest file is released when `deinit` is called. As another
/// option, one may call `toOwnedLock` to obtain a smaller object which can represent
/// the lock. `deinit` is safe to call whether or not `toOwnedLock` has been called.
pub fn hit(self: *Manifest) !bool {
const gpa = self.cache.gpa;
assert(self.manifest_file == null);
self.failed_file_index = null;
const ext = ".txt";
var manifest_file_path: [hex_digest_len + ext.len]u8 = undefined;
var bin_digest: BinDigest = undefined;
self.hash.hasher.final(&bin_digest);
self.hex_digest = binToHex(bin_digest);
self.hash.hasher = hasher_init;
self.hash.hasher.update(&bin_digest);
@memcpy(manifest_file_path[0..self.hex_digest.len], &self.hex_digest);
manifest_file_path[hex_digest_len..][0..ext.len].* = ext.*;
while (true) {
if (self.cache.manifest_dir.createFile(&manifest_file_path, .{
.read = true,
.truncate = false,
.lock = .exclusive,
.lock_nonblocking = self.want_shared_lock,
})) |manifest_file| {
self.manifest_file = manifest_file;
self.have_exclusive_lock = true;
break;
} else |err| switch (err) {
error.WouldBlock => {
self.manifest_file = try self.cache.manifest_dir.openFile(&manifest_file_path, .{
.mode = .read_write,
.lock = .shared,
});
break;
},
// There are no dir components, so you would think that this was
// unreachable, however we have observed on macOS two processes racing
// to do openat() with O_CREAT manifest in ENOENT.
error.FileNotFound => continue,
else => |e| return e,
}
}
self.want_refresh_timestamp = true;
const input_file_count = self.files.entries.len;
while (true) : (self.unhit(bin_digest, input_file_count)) {
const file_contents = try self.manifest_file.?.reader().readAllAlloc(gpa, manifest_file_size_max);
defer gpa.free(file_contents);
var any_file_changed = false;
var line_iter = mem.tokenizeScalar(u8, file_contents, '\n');
var idx: usize = 0;
if (if (line_iter.next()) |line| !std.mem.eql(u8, line, manifest_header) else true) {
if (try self.upgradeToExclusiveLock()) continue;
self.manifest_dirty = true;
while (idx < input_file_count) : (idx += 1) {
const ch_file = &self.files.keys()[idx];
self.populateFileHash(ch_file) catch |err| {
self.failed_file_index = idx;
return err;
};
}
return false;
}
while (line_iter.next()) |line| {
defer idx += 1;
var iter = mem.tokenizeScalar(u8, line, ' ');
const size = iter.next() orelse return error.InvalidFormat;
const inode = iter.next() orelse return error.InvalidFormat;
const mtime_nsec_str = iter.next() orelse return error.InvalidFormat;
const digest_str = iter.next() orelse return error.InvalidFormat;
const prefix_str = iter.next() orelse return error.InvalidFormat;
const file_path = iter.rest();
const stat_size = fmt.parseInt(u64, size, 10) catch return error.InvalidFormat;
const stat_inode = fmt.parseInt(fs.File.INode, inode, 10) catch return error.InvalidFormat;
const stat_mtime = fmt.parseInt(i64, mtime_nsec_str, 10) catch return error.InvalidFormat;
const file_bin_digest = b: {
if (digest_str.len != hex_digest_len) return error.InvalidFormat;
var bd: BinDigest = undefined;
_ = fmt.hexToBytes(&bd, digest_str) catch return error.InvalidFormat;
break :b bd;
};
const prefix = fmt.parseInt(u8, prefix_str, 10) catch return error.InvalidFormat;
if (prefix >= self.cache.prefixes_len) return error.InvalidFormat;
if (file_path.len == 0) return error.InvalidFormat;
const cache_hash_file = f: {
const prefixed_path: PrefixedPath = .{
.prefix = prefix,
.sub_path = file_path, // expires with file_contents
};
if (idx < input_file_count) {
const file = &self.files.keys()[idx];
if (!file.prefixed_path.eql(prefixed_path))
return error.InvalidFormat;
file.stat = .{
.size = stat_size,
.inode = stat_inode,
.mtime = stat_mtime,
};
file.bin_digest = file_bin_digest;
break :f file;
}
const gop = try self.files.getOrPutAdapted(gpa, prefixed_path, FilesAdapter{});
errdefer _ = self.files.pop();
if (!gop.found_existing) {
gop.key_ptr.* = .{
.prefixed_path = .{
.prefix = prefix,
.sub_path = try gpa.dupe(u8, file_path),
},
.contents = null,
.max_file_size = null,
.stat = .{
.size = stat_size,
.inode = stat_inode,
.mtime = stat_mtime,
},
.bin_digest = file_bin_digest,
};
}
break :f gop.key_ptr;
};
const pp = cache_hash_file.prefixed_path;
const dir = self.cache.prefixes()[pp.prefix].handle;
const this_file = dir.openFile(pp.sub_path, .{ .mode = .read_only }) catch |err| switch (err) {
error.FileNotFound => {
if (try self.upgradeToExclusiveLock()) continue;
return false;
},
else => return error.CacheUnavailable,
};
defer this_file.close();
const actual_stat = this_file.stat() catch |err| {
self.failed_file_index = idx;
return err;
};
const size_match = actual_stat.size == cache_hash_file.stat.size;
const mtime_match = actual_stat.mtime == cache_hash_file.stat.mtime;
const inode_match = actual_stat.inode == cache_hash_file.stat.inode;
if (!size_match or !mtime_match or !inode_match) {
self.manifest_dirty = true;
cache_hash_file.stat = .{
.size = actual_stat.size,
.mtime = actual_stat.mtime,
.inode = actual_stat.inode,
};
if (self.isProblematicTimestamp(cache_hash_file.stat.mtime)) {
// The actual file has an unreliable timestamp, force it to be hashed
cache_hash_file.stat.mtime = 0;
cache_hash_file.stat.inode = 0;
}
var actual_digest: BinDigest = undefined;
hashFile(this_file, &actual_digest) catch |err| {
self.failed_file_index = idx;
return err;
};
if (!mem.eql(u8, &cache_hash_file.bin_digest, &actual_digest)) {
cache_hash_file.bin_digest = actual_digest;
// keep going until we have the input file digests
any_file_changed = true;
}
}
if (!any_file_changed) {
self.hash.hasher.update(&cache_hash_file.bin_digest);
}
}
if (any_file_changed) {
if (try self.upgradeToExclusiveLock()) continue;
// cache miss
// keep the manifest file open
self.unhit(bin_digest, input_file_count);
return false;
}
if (idx < input_file_count) {
if (try self.upgradeToExclusiveLock()) continue;
self.manifest_dirty = true;
while (idx < input_file_count) : (idx += 1) {
const ch_file = &self.files.keys()[idx];
self.populateFileHash(ch_file) catch |err| {
self.failed_file_index = idx;
return err;
};
}
return false;
}
if (self.want_shared_lock) {
try self.downgradeToSharedLock();
}
return true;
}
}
pub fn unhit(self: *Manifest, bin_digest: BinDigest, input_file_count: usize) void {
// Reset the hash.
self.hash.hasher = hasher_init;
self.hash.hasher.update(&bin_digest);
// Remove files not in the initial hash.
while (self.files.count() != input_file_count) {
var file = self.files.pop();
file.key.deinit(self.cache.gpa);
}
for (self.files.keys()) |file| {
self.hash.hasher.update(&file.bin_digest);
}
}
fn isProblematicTimestamp(man: *Manifest, file_time: i128) bool {
// If the file_time is prior to the most recent problematic timestamp
// then we don't need to access the filesystem.
if (file_time < man.recent_problematic_timestamp)
return false;
// Next we will check the globally shared Cache timestamp, which is accessed
// from multiple threads.
man.cache.mutex.lock();
defer man.cache.mutex.unlock();
// Save the global one to our local one to avoid locking next time.
man.recent_problematic_timestamp = man.cache.recent_problematic_timestamp;
if (file_time < man.recent_problematic_timestamp)
return false;
// This flag prevents multiple filesystem writes for the same hit() call.
if (man.want_refresh_timestamp) {
man.want_refresh_timestamp = false;
var file = man.cache.manifest_dir.createFile("timestamp", .{
.read = true,
.truncate = true,
}) catch return true;
defer file.close();
// Save locally and also save globally (we still hold the global lock).
man.recent_problematic_timestamp = (file.stat() catch return true).mtime;
man.cache.recent_problematic_timestamp = man.recent_problematic_timestamp;
}
return file_time >= man.recent_problematic_timestamp;
}
fn populateFileHash(self: *Manifest, ch_file: *File) !void {
const pp = ch_file.prefixed_path;
const dir = self.cache.prefixes()[pp.prefix].handle;
const file = try dir.openFile(pp.sub_path, .{});
defer file.close();
const actual_stat = try file.stat();
ch_file.stat = .{
.size = actual_stat.size,
.mtime = actual_stat.mtime,
.inode = actual_stat.inode,
};
if (self.isProblematicTimestamp(ch_file.stat.mtime)) {
// The actual file has an unreliable timestamp, force it to be hashed
ch_file.stat.mtime = 0;
ch_file.stat.inode = 0;
}
if (ch_file.max_file_size) |max_file_size| {
if (ch_file.stat.size > max_file_size) {
return error.FileTooBig;
}
const contents = try self.cache.gpa.alloc(u8, @as(usize, @intCast(ch_file.stat.size)));
errdefer self.cache.gpa.free(contents);
// Hash while reading from disk, to keep the contents in the cpu cache while
// doing hashing.
var hasher = hasher_init;
var off: usize = 0;
while (true) {
// give me everything you've got, captain
const bytes_read = try file.read(contents[off..]);
if (bytes_read == 0) break;
hasher.update(contents[off..][0..bytes_read]);
off += bytes_read;
}
hasher.final(&ch_file.bin_digest);
ch_file.contents = contents;
} else {
try hashFile(file, &ch_file.bin_digest);
}
self.hash.hasher.update(&ch_file.bin_digest);
}
/// Add a file as a dependency of process being cached, after the initial hash has been
/// calculated. This is useful for processes that don't know all the files that
/// are depended on ahead of time. For example, a source file that can import other files
/// will need to be recompiled if the imported file is changed.
pub fn addFilePostFetch(self: *Manifest, file_path: []const u8, max_file_size: usize) ![]const u8 {
assert(self.manifest_file != null);
const gpa = self.cache.gpa;
const prefixed_path = try self.cache.findPrefix(file_path);
errdefer gpa.free(prefixed_path.sub_path);
const gop = try self.files.getOrPutAdapted(gpa, prefixed_path, FilesAdapter{});
errdefer _ = self.files.pop();
if (gop.found_existing) {
gpa.free(prefixed_path.sub_path);
return gop.key_ptr.contents.?;
}
gop.key_ptr.* = .{
.prefixed_path = prefixed_path,
.max_file_size = max_file_size,
.stat = undefined,
.bin_digest = undefined,
.contents = null,
};
self.files.lockPointers();
defer self.files.unlockPointers();
try self.populateFileHash(gop.key_ptr);
return gop.key_ptr.contents.?;
}
/// Add a file as a dependency of process being cached, after the initial hash has been
/// calculated.
///
/// This is useful for processes that don't know the all the files that are
/// depended on ahead of time. For example, a source file that can import
/// other files will need to be recompiled if the imported file is changed.
pub fn addFilePost(self: *Manifest, file_path: []const u8) !void {
assert(self.manifest_file != null);
const gpa = self.cache.gpa;
const prefixed_path = try self.cache.findPrefix(file_path);
errdefer gpa.free(prefixed_path.sub_path);
const gop = try self.files.getOrPutAdapted(gpa, prefixed_path, FilesAdapter{});
errdefer _ = self.files.pop();
if (gop.found_existing) {
gpa.free(prefixed_path.sub_path);
return;
}
gop.key_ptr.* = .{
.prefixed_path = prefixed_path,
.max_file_size = null,
.stat = undefined,
.bin_digest = undefined,
.contents = null,
};
self.files.lockPointers();
defer self.files.unlockPointers();
try self.populateFileHash(gop.key_ptr);
}
/// Like `addFilePost` but when the file contents have already been loaded from disk.
/// On success, cache takes ownership of `resolved_path`.
pub fn addFilePostContents(
self: *Manifest,
resolved_path: []u8,
bytes: []const u8,
stat: File.Stat,
) !void {
assert(self.manifest_file != null);
const gpa = self.cache.gpa;
const prefixed_path = try self.cache.findPrefixResolved(resolved_path);
errdefer gpa.free(prefixed_path.sub_path);
const gop = try self.files.getOrPutAdapted(gpa, prefixed_path, FilesAdapter{});
errdefer _ = self.files.pop();
if (gop.found_existing) {
gpa.free(prefixed_path.sub_path);
return;
}
const new_file = gop.key_ptr;
new_file.* = .{
.prefixed_path = prefixed_path,
.max_file_size = null,
.stat = stat,
.bin_digest = undefined,
.contents = null,
};
if (self.isProblematicTimestamp(new_file.stat.mtime)) {
// The actual file has an unreliable timestamp, force it to be hashed
new_file.stat.mtime = 0;
new_file.stat.inode = 0;
}
{
var hasher = hasher_init;
hasher.update(bytes);
hasher.final(&new_file.bin_digest);
}
self.hash.hasher.update(&new_file.bin_digest);
}
pub fn addDepFilePost(self: *Manifest, dir: fs.Dir, dep_file_basename: []const u8) !void {
assert(self.manifest_file != null);
return self.addDepFileMaybePost(dir, dep_file_basename);
}
fn addDepFileMaybePost(self: *Manifest, dir: fs.Dir, dep_file_basename: []const u8) !void {
const dep_file_contents = try dir.readFileAlloc(self.cache.gpa, dep_file_basename, manifest_file_size_max);
defer self.cache.gpa.free(dep_file_contents);
var error_buf = std.ArrayList(u8).init(self.cache.gpa);
defer error_buf.deinit();
var it: DepTokenizer = .{ .bytes = dep_file_contents };
while (it.next()) |token| {
switch (token) {
// We don't care about targets, we only want the prereqs
// Clang is invoked in single-source mode but other programs may not
.target, .target_must_resolve => {},
.prereq => |file_path| if (self.manifest_file == null) {
_ = try self.addFile(file_path, null);
} else try self.addFilePost(file_path),
.prereq_must_resolve => {
var resolve_buf = std.ArrayList(u8).init(self.cache.gpa);
defer resolve_buf.deinit();
try token.resolve(resolve_buf.writer());
if (self.manifest_file == null) {
_ = try self.addFile(resolve_buf.items, null);
} else try self.addFilePost(resolve_buf.items);
},
else => |err| {
try err.printError(error_buf.writer());
log.err("failed parsing {s}: {s}", .{ dep_file_basename, error_buf.items });
return error.InvalidDepFile;
},
}
}
}
/// Returns a hex encoded hash of the inputs.
pub fn final(self: *Manifest) HexDigest {
assert(self.manifest_file != null);
// We don't close the manifest file yet, because we want to
// keep it locked until the API user is done using it.
// We also don't write out the manifest yet, because until
// cache_release is called we still might be working on creating
// the artifacts to cache.
var bin_digest: BinDigest = undefined;
self.hash.hasher.final(&bin_digest);
return binToHex(bin_digest);
}
/// If `want_shared_lock` is true, this function automatically downgrades the
/// lock from exclusive to shared.
pub fn writeManifest(self: *Manifest) !void {
assert(self.have_exclusive_lock);
const manifest_file = self.manifest_file.?;
if (self.manifest_dirty) {
self.manifest_dirty = false;
var contents = std.ArrayList(u8).init(self.cache.gpa);
defer contents.deinit();
const writer = contents.writer();
try writer.writeAll(manifest_header ++ "\n");
for (self.files.keys()) |file| {
try writer.print("{d} {d} {d} {} {d} {s}\n", .{
file.stat.size,
file.stat.inode,
file.stat.mtime,
fmt.fmtSliceHexLower(&file.bin_digest),
file.prefixed_path.prefix,
file.prefixed_path.sub_path,
});
}
try manifest_file.setEndPos(contents.items.len);
try manifest_file.pwriteAll(contents.items, 0);
}
if (self.want_shared_lock) {
try self.downgradeToSharedLock();
}
}
fn downgradeToSharedLock(self: *Manifest) !void {
if (!self.have_exclusive_lock) return;
// WASI does not currently support flock, so we bypass it here.
// TODO: If/when flock is supported on WASI, this check should be removed.
// See https://github.com/WebAssembly/wasi-filesystem/issues/2
if (builtin.os.tag != .wasi or std.process.can_spawn or !builtin.single_threaded) {
const manifest_file = self.manifest_file.?;
try manifest_file.downgradeLock();
}
self.have_exclusive_lock = false;
}
fn upgradeToExclusiveLock(self: *Manifest) !bool {
if (self.have_exclusive_lock) return false;
assert(self.manifest_file != null);
// WASI does not currently support flock, so we bypass it here.
// TODO: If/when flock is supported on WASI, this check should be removed.
// See https://github.com/WebAssembly/wasi-filesystem/issues/2
if (builtin.os.tag != .wasi or std.process.can_spawn or !builtin.single_threaded) {
const manifest_file = self.manifest_file.?;
// Here we intentionally have a period where the lock is released, in case there are
// other processes holding a shared lock.
manifest_file.unlock();
try manifest_file.lock(.exclusive);
}
self.have_exclusive_lock = true;
return true;
}
/// Obtain only the data needed to maintain a lock on the manifest file.
/// The `Manifest` remains safe to deinit.
/// Don't forget to call `writeManifest` before this!
pub fn toOwnedLock(self: *Manifest) Lock {
const lock: Lock = .{
.manifest_file = self.manifest_file.?,
};
self.manifest_file = null;
return lock;
}
/// Releases the manifest file and frees any memory the Manifest was using.
/// `Manifest.hit` must be called first.
/// Don't forget to call `writeManifest` before this!
pub fn deinit(self: *Manifest) void {
if (self.manifest_file) |file| {
if (builtin.os.tag == .windows) {
// See Lock.release for why this is required on Windows
file.unlock();
}
file.close();
}
for (self.files.keys()) |*file| {
file.deinit(self.cache.gpa);
}
self.files.deinit(self.cache.gpa);
}
pub fn populateFileSystemInputs(man: *Manifest, buf: *std.ArrayListUnmanaged(u8)) Allocator.Error!void {
assert(@typeInfo(std.zig.Server.Message.PathPrefix).Enum.fields.len == man.cache.prefixes_len);
buf.clearRetainingCapacity();
const gpa = man.cache.gpa;
const files = man.files.keys();
if (files.len > 0) {
for (files) |file| {
try buf.ensureUnusedCapacity(gpa, file.prefixed_path.sub_path.len + 2);
buf.appendAssumeCapacity(file.prefixed_path.prefix + 1);
buf.appendSliceAssumeCapacity(file.prefixed_path.sub_path);
buf.appendAssumeCapacity(0);
}
// The null byte is a separator, not a terminator.
buf.items.len -= 1;
}
}
};
/// On operating systems that support symlinks, does a readlink. On other operating systems,
/// uses the file contents. Windows supports symlinks but only with elevated privileges, so
/// it is treated as not supporting symlinks.
pub fn readSmallFile(dir: fs.Dir, sub_path: []const u8, buffer: []u8) ![]u8 {
if (builtin.os.tag == .windows) {
return dir.readFile(sub_path, buffer);
} else {
return dir.readLink(sub_path, buffer);
}
}
/// On operating systems that support symlinks, does a symlink. On other operating systems,
/// uses the file contents. Windows supports symlinks but only with elevated privileges, so
/// it is treated as not supporting symlinks.
/// `data` must be a valid UTF-8 encoded file path and 255 bytes or fewer.
pub fn writeSmallFile(dir: fs.Dir, sub_path: []const u8, data: []const u8) !void {
assert(data.len <= 255);
if (builtin.os.tag == .windows) {
return dir.writeFile(.{ .sub_path = sub_path, .data = data });
} else {
return dir.symLink(data, sub_path, .{});
}
}
fn hashFile(file: fs.File, bin_digest: *[Hasher.mac_length]u8) !void {
var buf: [1024]u8 = undefined;
var hasher = hasher_init;
while (true) {
const bytes_read = try file.read(&buf);
if (bytes_read == 0) break;
hasher.update(buf[0..bytes_read]);
}
hasher.final(bin_digest);
}
// Create/Write a file, close it, then grab its stat.mtime timestamp.
fn testGetCurrentFileTimestamp(dir: fs.Dir) !i128 {
const test_out_file = "test-filetimestamp.tmp";
var file = try dir.createFile(test_out_file, .{
.read = true,
.truncate = true,
});
defer {
file.close();
dir.deleteFile(test_out_file) catch {};
}
return (try file.stat()).mtime;
}
test "cache file and then recall it" {
if (builtin.os.tag == .wasi) {
// https://github.com/ziglang/zig/issues/5437
return error.SkipZigTest;
}
var tmp = testing.tmpDir(.{});
defer tmp.cleanup();
const temp_file = "test.txt";
const temp_manifest_dir = "temp_manifest_dir";
try tmp.dir.writeFile(.{ .sub_path = temp_file, .data = "Hello, world!\n" });
// Wait for file timestamps to tick
const initial_time = try testGetCurrentFileTimestamp(tmp.dir);
while ((try testGetCurrentFileTimestamp(tmp.dir)) == initial_time) {
std.time.sleep(1);
}
var digest1: HexDigest = undefined;
var digest2: HexDigest = undefined;
{
var cache = Cache{
.gpa = testing.allocator,
.manifest_dir = try tmp.dir.makeOpenPath(temp_manifest_dir, .{}),
};
cache.addPrefix(.{ .path = null, .handle = tmp.dir });
defer cache.manifest_dir.close();
{
var ch = cache.obtain();
defer ch.deinit();
ch.hash.add(true);
ch.hash.add(@as(u16, 1234));
ch.hash.addBytes("1234");
_ = try ch.addFile(temp_file, null);
// There should be nothing in the cache
try testing.expectEqual(false, try ch.hit());
digest1 = ch.final();
try ch.writeManifest();
}
{
var ch = cache.obtain();
defer ch.deinit();
ch.hash.add(true);
ch.hash.add(@as(u16, 1234));
ch.hash.addBytes("1234");
_ = try ch.addFile(temp_file, null);
// Cache hit! We just "built" the same file
try testing.expect(try ch.hit());
digest2 = ch.final();
try testing.expectEqual(false, ch.have_exclusive_lock);
}
try testing.expectEqual(digest1, digest2);
}
}
test "check that changing a file makes cache fail" {
if (builtin.os.tag == .wasi) {
// https://github.com/ziglang/zig/issues/5437
return error.SkipZigTest;
}
var tmp = testing.tmpDir(.{});
defer tmp.cleanup();
const temp_file = "cache_hash_change_file_test.txt";
const temp_manifest_dir = "cache_hash_change_file_manifest_dir";
const original_temp_file_contents = "Hello, world!\n";
const updated_temp_file_contents = "Hello, world; but updated!\n";
try tmp.dir.writeFile(.{ .sub_path = temp_file, .data = original_temp_file_contents });
// Wait for file timestamps to tick
const initial_time = try testGetCurrentFileTimestamp(tmp.dir);
while ((try testGetCurrentFileTimestamp(tmp.dir)) == initial_time) {
std.time.sleep(1);
}
var digest1: HexDigest = undefined;
var digest2: HexDigest = undefined;
{
var cache = Cache{
.gpa = testing.allocator,
.manifest_dir = try tmp.dir.makeOpenPath(temp_manifest_dir, .{}),
};
cache.addPrefix(.{ .path = null, .handle = tmp.dir });
defer cache.manifest_dir.close();
{
var ch = cache.obtain();
defer ch.deinit();
ch.hash.addBytes("1234");
const temp_file_idx = try ch.addFile(temp_file, 100);
// There should be nothing in the cache
try testing.expectEqual(false, try ch.hit());
try testing.expect(mem.eql(u8, original_temp_file_contents, ch.files.keys()[temp_file_idx].contents.?));
digest1 = ch.final();
try ch.writeManifest();
}
try tmp.dir.writeFile(.{ .sub_path = temp_file, .data = updated_temp_file_contents });
{
var ch = cache.obtain();
defer ch.deinit();
ch.hash.addBytes("1234");
const temp_file_idx = try ch.addFile(temp_file, 100);
// A file that we depend on has been updated, so the cache should not contain an entry for it
try testing.expectEqual(false, try ch.hit());
// The cache system does not keep the contents of re-hashed input files.
try testing.expect(ch.files.keys()[temp_file_idx].contents == null);
digest2 = ch.final();
try ch.writeManifest();
}
try testing.expect(!mem.eql(u8, digest1[0..], digest2[0..]));
}
}
test "no file inputs" {
if (builtin.os.tag == .wasi) {
// https://github.com/ziglang/zig/issues/5437
return error.SkipZigTest;
}
var tmp = testing.tmpDir(.{});
defer tmp.cleanup();
const temp_manifest_dir = "no_file_inputs_manifest_dir";
var digest1: HexDigest = undefined;
var digest2: HexDigest = undefined;
var cache = Cache{
.gpa = testing.allocator,
.manifest_dir = try tmp.dir.makeOpenPath(temp_manifest_dir, .{}),
};
cache.addPrefix(.{ .path = null, .handle = tmp.dir });
defer cache.manifest_dir.close();
{
var man = cache.obtain();
defer man.deinit();
man.hash.addBytes("1234");
// There should be nothing in the cache
try testing.expectEqual(false, try man.hit());
digest1 = man.final();
try man.writeManifest();
}
{
var man = cache.obtain();
defer man.deinit();
man.hash.addBytes("1234");
try testing.expect(try man.hit());
digest2 = man.final();
try testing.expectEqual(false, man.have_exclusive_lock);
}
try testing.expectEqual(digest1, digest2);
}
test "Manifest with files added after initial hash work" {
if (builtin.os.tag == .wasi) {
// https://github.com/ziglang/zig/issues/5437
return error.SkipZigTest;
}
var tmp = testing.tmpDir(.{});
defer tmp.cleanup();
const temp_file1 = "cache_hash_post_file_test1.txt";
const temp_file2 = "cache_hash_post_file_test2.txt";
const temp_manifest_dir = "cache_hash_post_file_manifest_dir";
try tmp.dir.writeFile(.{ .sub_path = temp_file1, .data = "Hello, world!\n" });
try tmp.dir.writeFile(.{ .sub_path = temp_file2, .data = "Hello world the second!\n" });
// Wait for file timestamps to tick
const initial_time = try testGetCurrentFileTimestamp(tmp.dir);
while ((try testGetCurrentFileTimestamp(tmp.dir)) == initial_time) {
std.time.sleep(1);
}
var digest1: HexDigest = undefined;
var digest2: HexDigest = undefined;
var digest3: HexDigest = undefined;
{
var cache = Cache{
.gpa = testing.allocator,
.manifest_dir = try tmp.dir.makeOpenPath(temp_manifest_dir, .{}),
};
cache.addPrefix(.{ .path = null, .handle = tmp.dir });
defer cache.manifest_dir.close();
{
var ch = cache.obtain();
defer ch.deinit();
ch.hash.addBytes("1234");
_ = try ch.addFile(temp_file1, null);
// There should be nothing in the cache
try testing.expectEqual(false, try ch.hit());
_ = try ch.addFilePost(temp_file2);
digest1 = ch.final();
try ch.writeManifest();
}
{
var ch = cache.obtain();
defer ch.deinit();
ch.hash.addBytes("1234");
_ = try ch.addFile(temp_file1, null);
try testing.expect(try ch.hit());
digest2 = ch.final();
try testing.expectEqual(false, ch.have_exclusive_lock);
}
try testing.expect(mem.eql(u8, &digest1, &digest2));
// Modify the file added after initial hash
try tmp.dir.writeFile(.{ .sub_path = temp_file2, .data = "Hello world the second, updated\n" });
// Wait for file timestamps to tick
const initial_time2 = try testGetCurrentFileTimestamp(tmp.dir);
while ((try testGetCurrentFileTimestamp(tmp.dir)) == initial_time2) {
std.time.sleep(1);
}
{
var ch = cache.obtain();
defer ch.deinit();
ch.hash.addBytes("1234");
_ = try ch.addFile(temp_file1, null);
// A file that we depend on has been updated, so the cache should not contain an entry for it
try testing.expectEqual(false, try ch.hit());
_ = try ch.addFilePost(temp_file2);
digest3 = ch.final();
try ch.writeManifest();
}
try testing.expect(!mem.eql(u8, &digest1, &digest3));
}
}