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Use integer fractions for FILL_FACTOR & FREE_FACTOR in Map/Set #903

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Merged
merged 1 commit into from
Oct 12, 2019
Merged

Use integer fractions for FILL_FACTOR & FREE_FACTOR in Map/Set #903

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18 changes: 13 additions & 5 deletions std/assembly/map.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -11,11 +11,19 @@ const INITIAL_CAPACITY = 4;

// @ts-ignore: decorator
@inline
const FILL_FACTOR: f64 = 8 / 3;
const FILL_FACTOR_N = 8;

// @ts-ignore: decorator
@inline
const FREE_FACTOR: f64 = 3 / 4;
const FILL_FACTOR_D = 3;

// @ts-ignore: decorator
@inline
const FREE_FACTOR_N = 3;

// @ts-ignore: decorator
@inline
const FREE_FACTOR_D = 4;

/** Structure of a map entry. */
@unmanaged class MapEntry<K,V> {
Expand Down Expand Up @@ -122,7 +130,7 @@ export class Map<K,V> {
// check if rehashing is necessary
if (this.entriesOffset == this.entriesCapacity) {
this.rehash(
this.entriesCount < <i32>(this.entriesCapacity * FREE_FACTOR)
this.entriesCount < this.entriesCapacity * FREE_FACTOR_N / FREE_FACTOR_D
? this.bucketsMask // just rehash if 1/4+ entries are empty
: (this.bucketsMask << 1) | 1 // grow capacity to next 2^N
);
Expand Down Expand Up @@ -156,15 +164,15 @@ export class Map<K,V> {
var halfBucketsMask = this.bucketsMask >> 1;
if (
halfBucketsMask + 1 >= max<u32>(INITIAL_CAPACITY, this.entriesCount) &&
this.entriesCount < <i32>(this.entriesCapacity * FREE_FACTOR)
this.entriesCount < this.entriesCapacity * FREE_FACTOR_N / FREE_FACTOR_D
) this.rehash(halfBucketsMask);
return true;
}

private rehash(newBucketsMask: u32): void {
var newBucketsCapacity = <i32>(newBucketsMask + 1);
var newBuckets = new ArrayBuffer(newBucketsCapacity * <i32>BUCKET_SIZE);
var newEntriesCapacity = <i32>(newBucketsCapacity * FILL_FACTOR);
var newEntriesCapacity = newBucketsCapacity * FILL_FACTOR_N / FILL_FACTOR_D;
var newEntries = new ArrayBuffer(newEntriesCapacity * <i32>ENTRY_SIZE<K,V>());

// copy old entries to new entries
Expand Down
18 changes: 13 additions & 5 deletions std/assembly/set.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -10,11 +10,19 @@ const INITIAL_CAPACITY = 4;

// @ts-ignore: decorator
@inline
const FILL_FACTOR: f64 = 8 / 3;
const FILL_FACTOR_N = 8;

// @ts-ignore: decorator
@inline
const FREE_FACTOR: f64 = 3 / 4;
const FILL_FACTOR_D = 3;

// @ts-ignore: decorator
@inline
const FREE_FACTOR_N = 3;

// @ts-ignore: decorator
@inline
const FREE_FACTOR_D = 4;

/** Structure of a set entry. */
@unmanaged class SetEntry<K> {
Expand Down Expand Up @@ -100,7 +108,7 @@ export class Set<T> {
// check if rehashing is necessary
if (this.entriesOffset == this.entriesCapacity) {
this.rehash(
this.entriesCount < <i32>(this.entriesCapacity * FREE_FACTOR)
this.entriesCount < this.entriesCapacity * FREE_FACTOR_N / FREE_FACTOR_D
? this.bucketsMask // just rehash if 1/4+ entries are empty
: (this.bucketsMask << 1) | 1 // grow capacity to next 2^N
);
Expand Down Expand Up @@ -134,15 +142,15 @@ export class Set<T> {
var halfBucketsMask = this.bucketsMask >> 1;
if (
halfBucketsMask + 1 >= max<u32>(INITIAL_CAPACITY, this.entriesCount) &&
this.entriesCount < <i32>(this.entriesCapacity * FREE_FACTOR)
this.entriesCount < this.entriesCapacity * FREE_FACTOR_N / FREE_FACTOR_D
) this.rehash(halfBucketsMask);
return true;
}

private rehash(newBucketsMask: u32): void {
var newBucketsCapacity = <i32>(newBucketsMask + 1);
var newBuckets = new ArrayBuffer(newBucketsCapacity * <i32>BUCKET_SIZE);
var newEntriesCapacity = <i32>(newBucketsCapacity * FILL_FACTOR);
var newEntriesCapacity = newBucketsCapacity * FILL_FACTOR_N / FILL_FACTOR_D;
var newEntries = new ArrayBuffer(newEntriesCapacity * <i32>ENTRY_SIZE<T>());

// copy old entries to new entries
Expand Down
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