srctree

Igor Anić parent b9cca3b6 a21f9b6d
compress.xz: remove copyForwards from tight loop

In the example from the issue #19052 to_read holds 213_315_584uncompressed bytes. Calling read with small output results in manyshifts of that big buffer.This removes need to shift to_read after each read.

inline split

lib/std/compress/xz/block.zig added: 11, removed: 6, total 5

@@ -34,6 +34,7 @@ pub fn Decoder(comptime ReaderType: type) type {

check: xz.Check,

err: ?Error,

to_read: ArrayListUnmanaged(u8),

read_pos: usize,

block_count: usize,

fn init(allocator: Allocator, in_reader: ReaderType, check: xz.Check) !Self {

@@ -43,6 +44,7 @@ pub fn Decoder(comptime ReaderType: type) type {

.check = check,

.err = null,

.to_read = .{},

.read_pos = 0,

.block_count = 0,

};

}

@@ -57,13 +59,12 @@ pub fn Decoder(comptime ReaderType: type) type {

pub fn read(self: *Self, output: []u8) Error!usize {

while (true) {

if (self.to_read.items.len > 0) {

const input = self.to_read.items;

const input = self.to_read.items[self.read_pos..];

if (input.len > 0) {

const n = @min(input.len, output.len);

@memcpy(output[0..n], input[0..n]);

std.mem.copyForwards(u8, input, input[n..]);

self.to_read.shrinkRetainingCapacity(input.len - n);

if (self.to_read.items.len == 0 and self.err != null) {

self.read_pos += n;

if (self.read_pos == self.to_read.items.len and self.err != null) {

if (self.err.? == DecodeError.EndOfStreamWithNoError) {

return n;

}

@@ -77,6 +78,10 @@ pub fn Decoder(comptime ReaderType: type) type {

}

return self.err.?;

}

if (self.read_pos > 0) {

self.to_read.shrinkRetainingCapacity(0);

self.read_pos = 0;

}

self.readBlock() catch |e| {

self.err = e;

};