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up2k.js: 10x faster hashing on android-chrome
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when hashing files on android-chrome, read a contiguous range of
several chunks at a time, ensuring each read is at least 48 MiB
and then slice that cache into the correct chunksizes for hashing

especially on GrapheneOS Vanadium (where webworkers are forbidden),
improves worst-case speed (filesize <= 256 MiB) from 13 to 139 MiB/s

48M was chosen wrt RAM usage (48*4 MiB); a target read-size of
16M would have given 76 MiB/s, 32M = 117 MiB/s, and 64M = 154 MiB/s

additionally, on all platforms (not just android and/or chrome),
allow async hashing of <= 3 chunks in parallel on main-thread
when chunksize <= 48 MiB, and <= 2 at <= 96 MiB; this gives
decent speeds approaching that of webworkers (around 50%)

this is a new take on c06d928
which was removed in 184af0c
when a chrome-beta temporarily fixed the poor file-read performance
(afaict the fix was reverted and never made it to chrome stable)

as for why any of this is necessary,

the security features in android have the unfortunate side-effect
of making file-reads from web-browsers extremely expensive;
this is especially noticeable in android-chrome, where
file-hashing is painfully slow, around 9 MiB/s worst-case

this is due to a fixed-time overhead for each read operation;
reading 1 MiB takes 60 msec, while reading 16 MiB takes 112 msec
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@9001
9001 committed Jan 10, 2025
1 parent ac0a2da commit ec50788
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Showing 2 changed files with 68 additions and 13 deletions.
79 changes: 67 additions & 12 deletions copyparty/web/up2k.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -881,7 +881,7 @@ function up2k_init(subtle) {
bcfg_bind(uc, 'turbo', 'u2turbo', turbolvl > 1, draw_turbo);
bcfg_bind(uc, 'datechk', 'u2tdate', turbolvl < 3, null);
bcfg_bind(uc, 'az', 'u2sort', u2sort.indexOf('n') + 1, set_u2sort);
bcfg_bind(uc, 'hashw', 'hashw', !!WebAssembly && (!subtle || !CHROME || MOBILE || VCHROME >= 107), set_hashw);
bcfg_bind(uc, 'hashw', 'hashw', !!WebAssembly && !(CHROME && MOBILE) && (!subtle || !CHROME), set_hashw);
bcfg_bind(uc, 'upnag', 'upnag', false, set_upnag);
bcfg_bind(uc, 'upsfx', 'upsfx', false, set_upsfx);

Expand Down Expand Up @@ -1972,32 +1972,84 @@ function up2k_init(subtle) {
nchunk = 0,
chunksize = get_chunksize(t.size),
nchunks = Math.ceil(t.size / chunksize),
csz_mib = chunksize / 1048576,
tread = t.t_hashing,
cache_buf = null,
cache_car = 0,
cache_cdr = 0,
hashers = 0,
hashtab = {};

// resolving subtle.digest w/o worker takes 1sec on blur if the actx hack breaks
var use_workers = hws.length && !hws_ng && uc.hashw && (nchunks > 1 || document.visibilityState == 'hidden'),
hash_par = (!subtle && !use_workers) ? 0 : csz_mib < 48 ? 2 : csz_mib < 96 ? 1 : 0;

pvis.setab(t.n, nchunks);
pvis.move(t.n, 'bz');

if (hws.length && !hws_ng && uc.hashw && (nchunks > 1 || document.visibilityState == 'hidden'))
// resolving subtle.digest w/o worker takes 1sec on blur if the actx hack breaks
if (use_workers)
return wexec_hash(t, chunksize, nchunks);

var segm_next = function () {
if (nchunk >= nchunks || bpend)
return false;

var reader = new FileReader(),
nch = nchunk++,
var nch = nchunk++,
car = nch * chunksize,
cdr = Math.min(chunksize + car, t.size);

st.bytes.hashed += cdr - car;
st.etac.h++;

var orz = function (e) {
bpend--;
segm_next();
hash_calc(nch, e.target.result);
if (MOBILE && CHROME && st.slow_io === null && nch == 1 && cdr - car >= 1024 * 512) {
var spd = Math.floor((cdr - car) / (Date.now() + 1 - tread));
st.slow_io = spd < 40 * 1024;
console.log('spd {0}, slow: {1}'.format(spd, st.slow_io));
}

if (cdr <= cache_cdr && car >= cache_car) {
try {
var ofs = car - cache_car,
ofs2 = ofs + (cdr - car),
buf = cache_buf.subarray(ofs, ofs2);

hash_calc(nch, buf);
}
catch (ex) {
vis_exh(ex + '', 'up2k.js', '', '', ex);
}
return;
}

var reader = new FileReader(),
fr_cdr = cdr;

if (st.slow_io) {
var step = cdr - car,
tgt = 48 * 1048576;

while (step && fr_cdr - car < tgt)
fr_cdr += step;
if (fr_cdr - car > tgt && fr_cdr > cdr)
fr_cdr -= step;
if (fr_cdr > t.size)
fr_cdr = t.size;
}

var orz = function (e) {
bpend = 0;
var buf = e.target.result;
if (fr_cdr > cdr) {
cache_buf = new Uint8Array(buf);
cache_car = car;
cache_cdr = fr_cdr;
buf = cache_buf.subarray(0, cdr - car);
}
if (hashers < hash_par)
segm_next();

hash_calc(nch, buf);
};
reader.onload = function (e) {
try { orz(e); } catch (ex) { vis_exh(ex + '', 'up2k.js', '', '', ex); }
};
Expand All @@ -2024,17 +2076,20 @@ function up2k_init(subtle) {

toast.err(0, 'y o u b r o k e i t\nfile: ' + esc(t.name + '') + '\nerror: ' + err);
};
bpend++;
reader.readAsArrayBuffer(t.fobj.slice(car, cdr));
bpend = 1;
tread = Date.now();
reader.readAsArrayBuffer(t.fobj.slice(car, fr_cdr));

return true;
};

var hash_calc = function (nch, buf) {
hashers++;
var orz = function (hashbuf) {
var hslice = new Uint8Array(hashbuf).subarray(0, 33),
b64str = buf2b64(hslice);

hashers--;
hashtab[nch] = b64str;
t.hash.push(nch);
pvis.hashed(t);
Expand Down Expand Up @@ -3044,7 +3099,7 @@ function up2k_init(subtle) {
new_state = false;
fixed = true;
}
if (new_state === undefined)
if (new_state === undefined && preferred === undefined)
new_state = can_write ? false : have_up2k_idx ? true : undefined;
}

Expand Down
2 changes: 1 addition & 1 deletion copyparty/web/util.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,7 @@ var wah = '',
HTTPS = ('' + location).indexOf('https:') === 0,
TOUCH = 'ontouchstart' in window,
MOBILE = TOUCH,
CHROME = !!window.chrome,
CHROME = !!window.chrome, // safari=false
VCHROME = CHROME ? 1 : 0,
IE = /Trident\//.test(navigator.userAgent),
FIREFOX = ('netscape' in window) && / rv:/.test(navigator.userAgent),
Expand Down

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