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Fix histogram (#3150)

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* fix histogram

* remove outdated comment
This commit is contained in:
keorn 2016-11-03 20:15:27 +00:00 committed by Arkadiy Paronyan
parent f32c6af6c4
commit 0c2cfc9b6e
2 changed files with 42 additions and 14 deletions
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2
ethcore/src/tests/client.rs
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@ -217,7 +217,7 @@ fn can_generate_gas_price_histogram() {
let client = client_result.reference(); let client = client_result.reference();
let hist = client.gas_price_histogram(20, 5).unwrap(); let hist = client.gas_price_histogram(20, 5).unwrap();
let correct_hist = Histogram { bucket_bounds: vec_into![643,2293,3943,5593,7243,8893], counts: vec![4,2,4,6,3] }; let correct_hist = Histogram { bucket_bounds: vec_into![643, 2294, 3945, 5596, 7247, 8898], counts: vec![4,2,4,6,4] };
assert_eq!(hist, correct_hist); assert_eq!(hist, correct_hist);
} }

54
util/src/stats.rs
View File

@ -28,13 +28,17 @@ pub struct Histogram {
} }
impl Histogram { impl Histogram {
/// Histogram if a sorted corpus is at least fills the buckets. /// Histogram of a sorted corpus if it at least spans the buckets. Bounds are left closed.
pub fn new(corpus: &[U256], bucket_number: usize) -> Option<Histogram> { pub fn new(corpus: &[U256], bucket_number: usize) -> Option<Histogram> {
if corpus.len() <= bucket_number { return None; } if corpus.len() < 1 { return None; }
let corpus_end = corpus.last().expect("there are at least bucket_number elements; qed").clone(); let corpus_end = corpus.last().expect("there is at least 1 element; qed").clone();
// If there are extremely few transactions, go from zero. let corpus_start = corpus.first().expect("there is at least 1 element; qed").clone();
let corpus_start = corpus.first().expect("there are at least bucket_number elements; qed").clone(); // Bucket needs to be at least 1 wide.
let bucket_size = (corpus_end - corpus_start + 1.into()) / bucket_number.into(); let bucket_size = {
// Round up to get the entire corpus included.
let raw_bucket_size = (corpus_end - corpus_start + bucket_number.into()) / bucket_number.into();
if raw_bucket_size == 0.into() { 1.into() } else { raw_bucket_size }
};
let mut bucket_end = corpus_start + bucket_size; let mut bucket_end = corpus_start + bucket_size;
let mut bucket_bounds = vec![corpus_start; bucket_number + 1]; let mut bucket_bounds = vec![corpus_start; bucket_number + 1];
@ -42,10 +46,12 @@ impl Histogram {
let mut corpus_i = 0; let mut corpus_i = 0;
// Go through the corpus adding to buckets. // Go through the corpus adding to buckets.
for bucket in 0..bucket_number { for bucket in 0..bucket_number {
while corpus[corpus_i] < bucket_end { while corpus.get(corpus_i).map_or(false, |v| v < &bucket_end) {
// Initialized to size bucket_number above; iterates up to bucket_number; qed
counts[bucket] += 1; counts[bucket] += 1;
corpus_i += 1; corpus_i += 1;
} }
// Initialized to size bucket_number + 1 above; iterates up to bucket_number; subscript is in range; qed
bucket_bounds[bucket + 1] = bucket_end; bucket_bounds[bucket + 1] = bucket_end;
bucket_end = bucket_end + bucket_size; bucket_end = bucket_end + bucket_size;
} }
@ -62,14 +68,36 @@ mod tests {
#[test] #[test]
fn check_histogram() { fn check_histogram() {
let hist = Histogram::new(&vec_into![643,689,1408,2000,2296,2512,4250,4320,4842,4958,5804,6065,6098,6354,7002,7145,7845,8589,8593,8895], 5).unwrap(); let hist = Histogram::new(&vec_into![643,689,1408,2000,2296,2512,4250,4320,4842,4958,5804,6065,6098,6354,7002,7145,7845,8589,8593,8895], 5).unwrap();
let correct_bounds: Vec<U256> = vec_into![643,2293,3943,5593,7243,8893]; let correct_bounds: Vec<U256> = vec_into![643, 2294, 3945, 5596, 7247, 8898];
assert_eq!(Histogram { bucket_bounds: correct_bounds, counts: vec![4,2,4,6,3] }, hist); assert_eq!(Histogram { bucket_bounds: correct_bounds, counts: vec![4,2,4,6,4] }, hist);
assert!(Histogram::new(&vec_into![1, 2], 5).is_none());
} }
#[test] #[test]
fn should_not_panic_when_asking_for_bucket_too_big() { fn smaller_data_range_than_bucket_range() {
assert!(Histogram::new(&vec_into![1, 2], 2).is_none()); assert_eq!(
Histogram::new(&vec_into![1, 2, 2], 3),
Some(Histogram { bucket_bounds: vec_into![1, 2, 3, 4], counts: vec![1, 2, 0] })
);
}
#[test]
fn data_range_is_not_multiple_of_bucket_range() {
assert_eq!(
Histogram::new(&vec_into![1, 2, 5], 2),
Some(Histogram { bucket_bounds: vec_into![1, 4, 7], counts: vec![2, 1] })
);
}
#[test]
fn data_range_is_multiple_of_bucket_range() {
assert_eq!(
Histogram::new(&vec_into![1, 2, 6], 2),
Some(Histogram { bucket_bounds: vec_into![1, 4, 7], counts: vec![2, 1] })
);
}
#[test]
fn none_when_too_few_data() {
assert!(Histogram::new(&vec_into![], 1).is_none());
} }
} }