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WRStatsReader.php
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WRStatsReader.php
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<?php
namespace Wikimedia\WRStats;
/**
* Readers gather a batch of read operations, returning
* promises. The batch is executed when the first promise is resolved.
*
* @since 1.39
*/
class WRStatsReader {
/** @var StatsStore */
private $store;
/** @var array<string,MetricSpec> */
private $metricSpecs;
/** @var string[] */
private $prefixComponents;
/** @var float|int|null The UNIX timestamp used for the current time */
private $now;
/** @var bool[] Storage keys ready to be fetched */
private $queuedKeys = [];
/** @var int[] Unscaled integers returned by the store, indexed by key */
private $cachedValues = [];
/**
* @internal Use WRStatsFactory::createReader instead
* @param StatsStore $store
* @param array<string,array> $specs
* @param string|string[] $prefix
*/
public function __construct( StatsStore $store, $specs, $prefix ) {
$this->store = $store;
$this->metricSpecs = [];
foreach ( $specs as $name => $spec ) {
$this->metricSpecs[$name] = new MetricSpec( $spec );
}
$this->prefixComponents = is_array( $prefix ) ? $prefix : [ $prefix ];
if ( !count( $this->prefixComponents ) ) {
throw new WRStatsError( __METHOD__ .
': there must be at least one prefix component' );
}
}
/**
* Get a TimeRange for some period ending at the current time. Note that
* this will use the same value of the current time for subsequent calls
* until resetCurrentTime() is called.
*
* @param int|float $numSeconds
* @return TimeRange
*/
public function latest( $numSeconds ) {
$now = $this->now();
return new TimeRange( $now - $numSeconds, $now );
}
/**
* Get a specified time range
*
* @param int|float $start The UNIX time of the start of the range
* @param int|float $end The UNIX time of the end of the range
* @return TimeRange
*/
public function timeRange( $start, $end ) {
return new TimeRange( $start, $end );
}
/**
* Queue a fetch operation.
*
* @param string $metricName The metric name, the key into $specs.
* @param EntityKey|null $entity Additional storage key components
* @param TimeRange $range The time range to fetch
* @return RatePromise
*/
public function getRate( $metricName, ?EntityKey $entity, TimeRange $range ) {
$metricSpec = $this->metricSpecs[$metricName] ?? null;
if ( $metricSpec === null ) {
throw new WRStatsError( "Unrecognised metric \"$metricName\"" );
}
$entity ??= new LocalEntityKey;
$now = $this->now();
$seqSpec = null;
foreach ( $metricSpec->sequences as $seqSpec ) {
$seqStart = $now - $seqSpec->softExpiry;
if ( $seqStart <= $range->start ) {
break;
}
}
if ( !$seqSpec ) {
// This check exists to make Phan happy.
// It should never fail since we apply normalization in MetricSpec::__construct()
throw new WRStatsError( 'There should have been at least one sequence' );
}
$timeStep = $seqSpec->timeStep;
$firstBucket = (int)( $range->start / $timeStep );
$lastBucket = (int)ceil( $range->end / $timeStep );
for ( $bucket = $firstBucket; $bucket <= $lastBucket; $bucket++ ) {
$key = $this->store->makeKey(
$this->prefixComponents,
[ $metricName, $seqSpec->name, $bucket ],
$entity
);
if ( !isset( $this->cachedValues[$key] ) ) {
$this->queuedKeys[$key] = true;
}
}
return new RatePromise( $this, $metricName, $entity, $metricSpec, $seqSpec, $range );
}
/**
* Queue a batch of fetch operations for different metrics with the same
* time range.
*
* @param string[] $metricNames
* @param EntityKey|null $entity
* @param TimeRange $range
* @return RatePromise[]
*/
public function getRates( $metricNames, ?EntityKey $entity, TimeRange $range ) {
$rates = [];
foreach ( $metricNames as $name ) {
$rates[$name] = $this->getRate( $name, $entity, $range );
}
return $rates;
}
/**
* Perform any queued fetch operations.
*/
public function fetch() {
if ( !$this->queuedKeys ) {
return;
}
$this->cachedValues += $this->store->query( array_keys( $this->queuedKeys ) );
$this->queuedKeys = [];
}
/**
* Set the current time to be used in latest() etc.
*
* @param int|float $now
*/
public function setCurrentTime( $now ) {
$this->now = $now;
}
/**
* Clear the current time so that it will be filled with the real current
* time on the next call.
*/
public function resetCurrentTime() {
$this->now = null;
}
/**
* @return float|int
*/
private function now() {
$this->now ??= microtime( true );
return $this->now;
}
/**
* @internal Utility for resolution in RatePromise
* @param string $metricName
* @param EntityKey $entity
* @param MetricSpec $metricSpec
* @param SequenceSpec $seqSpec
* @param TimeRange $range
* @return float|int
*/
public function internalGetCount(
$metricName,
EntityKey $entity,
MetricSpec $metricSpec,
SequenceSpec $seqSpec,
TimeRange $range
) {
$this->fetch();
$timeStep = $seqSpec->timeStep;
$firstBucket = (int)( $range->start / $timeStep );
$lastBucket = (int)( $range->end / $timeStep );
$now = $this->now();
$total = 0;
for ( $bucket = $firstBucket; $bucket <= $lastBucket; $bucket++ ) {
$key = $this->store->makeKey(
$this->prefixComponents,
[ $metricName, $seqSpec->name, $bucket ],
$entity
);
$value = $this->cachedValues[$key] ?? 0;
if ( !$value ) {
continue;
} elseif ( $bucket === $firstBucket ) {
if ( $bucket === $lastBucket ) {
// It can be assumed that there are zero events in the future
$bucketStartTime = $bucket * $timeStep;
$rateInterpolationEndTime = min( $bucketStartTime + $timeStep, $now );
$interpolationDuration = $rateInterpolationEndTime - $bucketStartTime;
if ( $interpolationDuration > 0 ) {
$total += $value * $range->getDuration() / $interpolationDuration;
}
} else {
$overlapDuration = max( ( $bucket + 1 ) * $timeStep - $range->start, 0 );
$total += $value * $overlapDuration / $timeStep;
}
} elseif ( $bucket === $lastBucket ) {
// It can be assumed that there are zero events in the future
$bucketStartTime = $bucket * $timeStep;
$rateInterpolationEndTime = min( $bucketStartTime + $timeStep, $now );
$overlapDuration = max( $range->end - $bucketStartTime, 0 );
$interpolationDuration = $rateInterpolationEndTime - $bucketStartTime;
if ( $overlapDuration === $interpolationDuration ) {
// Special case for 0/0 -- current time exactly on boundary.
$total += $value;
} elseif ( $interpolationDuration > 0 ) {
$total += $value * $overlapDuration / $interpolationDuration;
}
} else {
$total += $value;
}
}
// Round to nearest resolution step for nicer display
$rounded = round( $total ) * $metricSpec->resolution;
// Convert to integer if integer is expected
if ( is_int( $metricSpec->resolution ) ) {
$rounded = (int)$rounded;
}
return $rounded;
}
/**
* Resolve a batch of RatePromise objects, returning their counter totals,
* indexed as in the input array.
*
* @param array<mixed,RatePromise> $rates
* @return array<mixed,float|int>
*/
public function total( $rates ) {
$result = [];
foreach ( $rates as $key => $rate ) {
$result[$key] = $rate->total();
}
return $result;
}
/**
* Resolve a batch of RatePromise objects, returning their per-second rates.
*
* @param array<mixed,RatePromise> $rates
* @return array<mixed,float>
*/
public function perSecond( $rates ) {
$result = [];
foreach ( $rates as $key => $rate ) {
$result[$key] = $rate->perSecond();
}
return $result;
}
/**
* Resolve a batch of RatePromise objects, returning their per-minute rates.
*
* @param array<mixed,RatePromise> $rates
* @return array<mixed,float>
*/
public function perMinute( $rates ) {
$result = [];
foreach ( $rates as $key => $rate ) {
$result[$key] = $rate->perMinute();
}
return $result;
}
/**
* Resolve a batch of RatePromise objects, returning their per-hour rates.
*
* @param array<mixed,RatePromise> $rates
* @return array<mixed,float>
*/
public function perHour( $rates ) {
$result = [];
foreach ( $rates as $key => $rate ) {
$result[$key] = $rate->perHour();
}
return $result;
}
/**
* Resolve a batch of RatePromise objects, returning their per-day rates.
*
* @param array<mixed,RatePromise> $rates
* @return array<mixed,float>
*/
public function perDay( $rates ) {
$result = [];
foreach ( $rates as $key => $rate ) {
$result[$key] = $rate->perDay();
}
return $result;
}
}

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WRStatsReader.php (8 KB)

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