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Order HNTrie nodes alphabetically to allow for early bailout

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This commit implements the alphabetical ordering of HNTrie
nodes, so as to make it possible to bail out early at
HNTrie.matches() time.

Contrary to what I expected, there is no performance gain
observed to HNTrie.matches() as per benchmarks -- I find
the results perplexing.

Because of this I will revert this commit immediately.
The purpose of this commit is to record the changes so
that I can bring them back to life in the future whenever
I want to investigate further.
This commit is contained in:
Raymond Hill 2019-04-30 06:47:54 -04:00
parent a73024ad7b
commit f5f9e05071
No known key found for this signature in database
GPG Key ID: 25E1490B761470C2
1 changed files with 34 additions and 8 deletions
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42
src/js/hntrie.js
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@ -181,12 +181,14 @@ const HNTrieContainer = class {
if ( ineedle === 0 ) { return -1; }
ineedle -= 1;
let c = this.buf[ineedle];
let v, i0;
let v, i0, diff;
// find first segment with a first-character match
for (;;) {
v = this.buf32[icell+2];
i0 = char0 + (v & 0x00FFFFFF);
if ( this.buf[i0] === c ) { break; }
diff = this.buf[i0] - c;
if ( diff === 0 ) { break; }
if ( diff > 0 ) { return -1; }
icell = this.buf32[icell+0];
if ( icell === 0 ) { return -1; }
}
@ -254,7 +256,7 @@ const HNTrieContainer = class {
}
//
const char0 = this.buf32[HNTRIE_CHAR0_SLOT];
let inext;
let iprevious = iroot, diff, inext;
// find a matching cell: move down
for (;;) {
const vseg = this.buf32[icell+2];
@ -263,21 +265,38 @@ const HNTrieContainer = class {
// remainder is at label boundary? if yes, no need to add
// the rest since the shortest match is always reported
if ( this.buf[lhnchar-1] === 0x2E /* '.' */ ) { return -1; }
iprevious = icell;
icell = this.buf32[icell+1];
continue;
}
let isegchar0 = char0 + (vseg & 0x00FFFFFF);
// if first character is no match, move to next descendant
if ( this.buf[isegchar0] !== this.buf[lhnchar-1] ) {
diff = this.buf[isegchar0] - this.buf[lhnchar-1];
// current cell character greater than target character: insert
// a new node before current cell
if ( diff > 0 ) {
const inew = this.addCell(icell, 0, this.addSegment(lhnchar));
if ( icell === this.buf32[iprevious+0] ) {
this.buf32[iprevious+0] = inew;
} else /* if ( icell === this.buf32[iprevious+1] ) */ {
this.buf32[iprevious+1] = inew;
}
return 1;
}
// current cell character lesser than target character: keep
// looking
if ( diff !== 0 ) {
inext = this.buf32[icell+0];
// no match found: insert a new leaf descendant
if ( inext === 0 ) {
this.buf32[icell+0] = this.addCell(0, 0, this.addSegment(lhnchar));
return 1;
}
iprevious = icell;
icell = inext;
continue;
}
// 1st character was tested
// current cell character matches: 1st character was tested
let isegchar = 1;
lhnchar -= 1;
// find 1st mismatch in rest of segment
@ -286,7 +305,8 @@ const HNTrieContainer = class {
for (;;) {
if ( isegchar === lsegchar ) { break; }
if ( lhnchar === 0 ) { break; }
if ( this.buf[isegchar0+isegchar] !== this.buf[lhnchar-1] ) { break; }
diff = this.buf[isegchar0+isegchar] - this.buf[lhnchar-1];
if ( diff !== 0 ) { break; }
isegchar += 1;
lhnchar -= 1;
}
@ -304,6 +324,7 @@ const HNTrieContainer = class {
// needle remainder: yes
else {
if ( inext !== 0 ) {
iprevious = icell;
icell = inext;
continue;
}
@ -326,14 +347,19 @@ const HNTrieContainer = class {
this.buf32[icell+1],
lsegchar - isegchar << 24 | isegchar0 + isegchar
);
this.buf32[icell+1] = inext;
// needle remainder: no = need boundary cell
if ( lhnchar === 0 ) {
this.buf32[icell+1] = this.addCell(0, inext, 0);
}
// needle remainder: yes = need new cell for remaining characters
else {
this.buf32[inext+0] = this.addCell(0, 0, this.addSegment(lhnchar));
const isegment = this.addSegment(lhnchar);
if ( diff > 0 ) {
this.buf32[icell+1] = this.addCell(inext, 0, isegment);
} else {
this.buf32[icell+1] = inext;
this.buf32[inext+0] = this.addCell(0, 0, isegment);
}
}
}
return 1;