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https://codeberg.org/ziglang/zig.git
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std.Io.Reader: use readVec for fill functions
readVec has two updated responsibilities: 1. it must respect any existing already buffered data. 2. it must write to the buffer if data is empty
This commit is contained in:
Andrew Kelley
parent
e17a050bc6
commit
04fe1bfe3c
2 changed files with 123 additions and 65 deletions
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@ -70,13 +70,14 @@ pub const VTable = struct {
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/// Returns number of bytes written to `data`.
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///
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/// `data` may not have nonzero length.
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/// `data` must have nonzero length. `data[0]` may have zero length, in
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/// which case the implementation must write to `Reader.buffer`.
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///
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/// `data` may not contain an alias to `Reader.buffer`.
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///
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/// `data` is mutable because the implementation may to temporarily modify
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/// the fields in order to handle partial reads. Implementations must
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/// restore the original value before returning.
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/// `data` is mutable because the implementation may temporarily modify the
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/// fields in order to handle partial reads. Implementations must restore
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/// the original value before returning.
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///
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/// Implementations may ignore `data`, writing directly to `Reader.buffer`,
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/// modifying `seek` and `end` accordingly, and returning 0 from this
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@ -421,23 +422,29 @@ pub fn readVec(r: *Reader, data: [][]u8) Error!usize {
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/// Writes to `Reader.buffer` or `data`, whichever has larger capacity.
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pub fn defaultReadVec(r: *Reader, data: [][]u8) Error!usize {
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assert(r.seek == r.end);
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r.seek = 0;
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r.end = 0;
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const first = data[0];
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const direct = first.len >= r.buffer.len;
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if (r.seek == r.end and first.len >= r.buffer.len) {
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var writer: Writer = .{
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.buffer = first,
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.end = 0,
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.vtable = &.{ .drain = Writer.fixedDrain },
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};
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const limit: Limit = .limited(writer.buffer.len - writer.end);
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return r.vtable.stream(r, &writer, limit) catch |err| switch (err) {
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error.WriteFailed => unreachable,
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else => |e| return e,
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};
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}
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var writer: Writer = .{
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.buffer = if (direct) first else r.buffer,
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.end = 0,
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.buffer = r.buffer,
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.end = r.end,
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.vtable = &.{ .drain = Writer.fixedDrain },
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};
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const limit: Limit = .limited(writer.buffer.len - writer.end);
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const n = r.vtable.stream(r, &writer, limit) catch |err| switch (err) {
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r.end += r.vtable.stream(r, &writer, limit) catch |err| switch (err) {
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error.WriteFailed => unreachable,
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else => |e| return e,
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};
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if (direct) return n;
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r.end += n;
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return 0;
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}
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@ -1059,17 +1066,8 @@ pub fn fill(r: *Reader, n: usize) Error!void {
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/// increasing by a factor of 5 or more.
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fn fillUnbuffered(r: *Reader, n: usize) Error!void {
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try rebase(r, n);
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var writer: Writer = .{
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.buffer = r.buffer,
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.vtable = &.{ .drain = Writer.fixedDrain },
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};
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while (r.end < r.seek + n) {
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writer.end = r.end;
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r.end += r.vtable.stream(r, &writer, .limited(r.buffer.len - r.end)) catch |err| switch (err) {
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error.WriteFailed => unreachable,
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error.ReadFailed, error.EndOfStream => |e| return e,
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};
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}
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var bufs: [1][]u8 = .{""};
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while (r.end < r.seek + n) _ = try r.vtable.readVec(r, &bufs);
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}
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/// Without advancing the seek position, does exactly one underlying read, filling the buffer as
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@ -1079,15 +1077,8 @@ fn fillUnbuffered(r: *Reader, n: usize) Error!void {
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/// Asserts buffer capacity is at least 1.
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pub fn fillMore(r: *Reader) Error!void {
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try rebase(r, 1);
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var writer: Writer = .{
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.buffer = r.buffer,
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.end = r.end,
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.vtable = &.{ .drain = Writer.fixedDrain },
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};
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r.end += r.vtable.stream(r, &writer, .limited(r.buffer.len - r.end)) catch |err| switch (err) {
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error.WriteFailed => unreachable,
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else => |e| return e,
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};
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var bufs: [1][]u8 = .{""};
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_ = try r.vtable.readVec(r, &bufs);
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}
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/// Returns the next byte from the stream or returns `error.EndOfStream`.
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@ -1796,18 +1787,26 @@ pub fn Hashed(comptime Hasher: type) type {
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fn readVec(r: *Reader, data: [][]u8) Error!usize {
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const this: *@This() = @alignCast(@fieldParentPtr("reader", r));
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const n = try this.in.readVec(data);
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var vecs: [8][]u8 = undefined; // Arbitrarily chosen amount.
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const dest_n, const data_size = try r.writableVector(&vecs, data);
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const dest = vecs[0..dest_n];
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const n = try this.in.readVec(dest);
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var remaining: usize = n;
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for (data) |slice| {
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for (dest) |slice| {
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if (remaining < slice.len) {
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this.hasher.update(slice[0..remaining]);
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return n;
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remaining = 0;
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break;
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} else {
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remaining -= slice.len;
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this.hasher.update(slice);
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}
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}
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assert(remaining == 0);
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if (n > data_size) {
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r.end += n - data_size;
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return data_size;
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}
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return n;
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}
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@ -1824,17 +1823,24 @@ pub fn Hashed(comptime Hasher: type) type {
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pub fn writableVectorPosix(r: *Reader, buffer: []std.posix.iovec, data: []const []u8) Error!struct { usize, usize } {
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var i: usize = 0;
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var n: usize = 0;
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for (data) |buf| {
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if (buffer.len - i == 0) return .{ i, n };
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if (r.seek == r.end) {
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for (data) |buf| {
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if (buffer.len - i == 0) return .{ i, n };
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if (buf.len != 0) {
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buffer[i] = .{ .base = buf.ptr, .len = buf.len };
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i += 1;
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n += buf.len;
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}
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}
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const buf = r.buffer;
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if (buf.len != 0) {
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r.seek = 0;
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r.end = 0;
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buffer[i] = .{ .base = buf.ptr, .len = buf.len };
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i += 1;
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n += buf.len;
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}
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}
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assert(r.seek == r.end);
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const buf = r.buffer;
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if (buf.len != 0) {
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} else {
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const buf = r.buffer[r.end..];
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buffer[i] = .{ .base = buf.ptr, .len = buf.len };
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i += 1;
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}
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@ -1848,28 +1854,62 @@ pub fn writableVectorWsa(
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) Error!struct { usize, usize } {
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var i: usize = 0;
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var n: usize = 0;
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for (data) |buf| {
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if (buffer.len - i == 0) return .{ i, n };
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if (buf.len == 0) continue;
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if (std.math.cast(u32, buf.len)) |len| {
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buffer[i] = .{ .buf = buf.ptr, .len = len };
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i += 1;
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n += len;
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continue;
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}
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buffer[i] = .{ .buf = buf.ptr, .len = std.math.maxInt(u32) };
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i += 1;
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n += std.math.maxInt(u32);
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return .{ i, n };
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}
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assert(r.seek == r.end);
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const buf = r.buffer;
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if (buf.len != 0) {
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if (std.math.cast(u32, buf.len)) |len| {
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buffer[i] = .{ .buf = buf.ptr, .len = len };
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} else {
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if (r.seek == r.end) {
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for (data) |buf| {
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if (buffer.len - i == 0) return .{ i, n };
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if (buf.len == 0) continue;
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if (std.math.cast(u32, buf.len)) |len| {
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buffer[i] = .{ .buf = buf.ptr, .len = len };
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i += 1;
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n += len;
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continue;
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}
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buffer[i] = .{ .buf = buf.ptr, .len = std.math.maxInt(u32) };
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i += 1;
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n += std.math.maxInt(u32);
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return .{ i, n };
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}
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const buf = r.buffer;
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if (buf.len != 0) {
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r.seek = 0;
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r.end = 0;
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if (std.math.cast(u32, buf.len)) |len| {
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buffer[i] = .{ .buf = buf.ptr, .len = len };
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} else {
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buffer[i] = .{ .buf = buf.ptr, .len = std.math.maxInt(u32) };
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}
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i += 1;
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}
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} else {
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buffer[i] = .{
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.buf = r.buffer.ptr + r.end,
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.len = @min(std.math.maxInt(u32), r.buffer.len - r.end),
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};
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i += 1;
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}
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return .{ i, n };
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}
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pub fn writableVector(r: *Reader, buffer: [][]u8, data: []const []u8) Error!struct { usize, usize } {
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var i: usize = 0;
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var n: usize = 0;
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if (r.seek == r.end) {
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for (data) |buf| {
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if (buffer.len - i == 0) return .{ i, n };
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if (buf.len != 0) {
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buffer[i] = buf;
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i += 1;
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n += buf.len;
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}
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}
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if (r.buffer.len != 0) {
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r.seek = 0;
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r.end = 0;
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buffer[i] = r.buffer;
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i += 1;
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}
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} else {
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buffer[i] = r.buffer[r.end..];
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i += 1;
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}
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return .{ i, n };
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@ -1312,7 +1312,16 @@ pub const Reader = struct {
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if (is_windows) {
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// Unfortunately, `ReadFileScatter` cannot be used since it
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// requires page alignment.
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return readPositional(r, data[0]);
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assert(io_reader.seek == io_reader.end);
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io_reader.seek = 0;
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io_reader.end = 0;
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const first = data[0];
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if (first.len >= io_reader.buffer.len) {
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return readPositional(r, first);
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} else {
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io_reader.end += try readPositional(r, io_reader.buffer);
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return 0;
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}
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}
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var iovecs_buffer: [max_buffers_len]posix.iovec = undefined;
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const dest_n, const data_size = try io_reader.writableVectorPosix(&iovecs_buffer, data);
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@ -1352,7 +1361,16 @@ pub const Reader = struct {
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if (is_windows) {
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// Unfortunately, `ReadFileScatter` cannot be used since it
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// requires page alignment.
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return readStreaming(r, data[0]);
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assert(io_reader.seek == io_reader.end);
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io_reader.seek = 0;
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io_reader.end = 0;
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const first = data[0];
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if (first.len >= io_reader.buffer.len) {
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return readStreaming(r, first);
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} else {
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io_reader.end += try readStreaming(r, io_reader.buffer);
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return 0;
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}
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}
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var iovecs_buffer: [max_buffers_len]posix.iovec = undefined;
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const dest_n, const data_size = try io_reader.writableVectorPosix(&iovecs_buffer, data);
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