On Tuesday, 16 January 2024 at 21:15:19 UTC, Renato wrote:
For the record (I already posted this on GitHub)... here's [my
current fastest
solution](https://github.com/renatoathaydes/prechelt-phone-number-encoding/blob/dlang-key-hash-incremental/src/d/src/dencoder.d) time using the same algorithm as Rust ...
[...]
... what I am really curious about is what the code I wrote is
doing wrong that causes it to run 4x slower than Rust despite
doing "the same thing"...
It's a GC allocations fest. Things like this make it slow:
```diff
{
- string digit = [digits[0]];
+ string digit = digits[0 .. 1];
words.insertBack(digit);
```
And at the top is the associative array lookup (when profiling
the handling of the "phones_1_000_000_with_empty.txt" input file):
```
36.85% dencoder dencoder [.] _aaInX
12.38% dencoder dencoder [.] void
dencoder.printTranslations(immutable(char)[][][dencoder.Key],
dencoder.ISolutionHandler, immutable(char)[], immutable(char)[],
std.container.array.Array!(immutable(char)[]).Array)
6.43% dencoder dencoder [.] nothrow @nogc
scope void core.internal.gc.impl.conservative.gc.Gcx.mark!(false,
true,
true).mark(core.internal.gc.impl.conservative.gc.Gcx.ScanRange!(false).ScanRange)
4.53% dencoder dencoder [.] pure @safe void
std.algorithm.iteration.FilterResult!(dencoder.main(immutable(char)[][]).__lambda12, immutable(char)[]).FilterResult.popFront()
4.08% dencoder dencoder [.]
_d_array_slice_copy
2.43% dencoder dencoder [.] _d_newarrayU
2.21% dencoder dencoder [.] shared nothrow
@nogc @trusted void core.internal.spinlock.SpinLock.lock()
2.00% dencoder dencoder [.] pure @safe void
std.array.Appender!(immutable(char)[]).Appender.put!(dchar).put(dchar)
1.91% dencoder dencoder [.] nothrow void*
core.internal.gc.impl.conservative.gc.Gcx.smallAlloc(ulong, ref
ulong, uint, const(TypeInfo))
1.67% dencoder dencoder [.]
_DThn16_4core8internal2gc4impl12conservativeQw14ConservativeGC6qallocMFNbmkMxC8TypeInfoZSQDd6memory8BlkInfo_
1.66% dencoder dencoder [.] pure nothrow
@nogc scope @trusted ulong
core.internal.gc.bits.GCBits.setLocked(ulong)
1.60% dencoder dencoder [.] const pure
nothrow @trusted ulong object.TypeInfo_Struct.getHash(scope
const(void*))
1.53% dencoder dencoder [.] nothrow @safe
void
core.internal.util.array.enforceRawArraysConformable(const(char[]), const(ulong), const(void[]), const(void[]), const(bool))
1.49% dencoder dencoder [.] nothrow void*
core.internal.gc.impl.conservative.gc.ConservativeGC.runLocked!(core.internal.gc.impl.conservative.gc.ConservativeGC.mallocNoSync(ulong, uint, ref ulong, const(TypeInfo)), core.internal.gc.impl.conservative.gc.mallocTime, core.internal.gc.impl.conservative.gc.numMallocs, ulong, uint, ulong, const(TypeInfo)).runLocked(ref ulong, ref uint, ref ulong, ref const(TypeInfo))
1.27% dencoder dencoder [.] pure nothrow
@safe void
std.array.Appender!(immutable(char)[]).Appender.ensureAddable(ulong)
0.81% dencoder dencoder [.] pure @property
@safe dchar
std.algorithm.iteration.FilterResult!(dencoder.main(immutable(char)[][]).__lambda12, immutable(char)[]).FilterResult.front()
0.79% dencoder dencoder [.] nothrow @safe
void core.internal.util.array._enforceNoOverlap(const(char[]),
ulong, ulong, const(ulong))
0.74% dencoder dencoder [.] nothrow void
core.internal.gc.impl.conservative.gc.Pool.setBits(ulong, uint)
0.73% dencoder dencoder [.] pure @safe void
std.array.Appender!(immutable(char)[]).Appender.put!(std.algorithm.iteration.FilterResult!(dencoder.main(immutable(char)[][]).__lambda12, immutable(char)[]).FilterResult).put(std.algorithm.iteration.FilterResult!(dencoder.main(immutable(char)[][]).__lambda12, immutable(char)[]).FilterResult)
0.70% dencoder dencoder [.] pure @safe ulong
std.range.primitives.walkLength!(std.algorithm.iteration.FilterResult!(dencoder.main(immutable(char)[][]).__lambda12, immutable(char)[]).FilterResult).walkLength(std.algorithm.iteration.FilterResult!(dencoder.main(immutable(char)[][]).__lambda12, immutable(char)[]).FilterResult)
0.60% dencoder dencoder [.] bool
dencoder.lastItemIsDigit(std.container.array.Array!(immutable(char)[]).Array)
0.54% dencoder dencoder [.] _d_newarrayT
[...]
```
