- private static double calculateNewRateLimit(Timer commitTimer, DatastoreContext context) {
- if(commitTimer == null) {
- // This can happen in unit tests.
- return 0;
- }
-
- Snapshot timerSnapshot = commitTimer.getSnapshot();
- double newRateLimit = 0;
-
- long commitTimeoutInSeconds = context.getShardTransactionCommitTimeoutInSeconds();
- long commitTimeoutInNanos = TimeUnit.SECONDS.toNanos(commitTimeoutInSeconds);
-
- // Find the time that it takes for transactions to get executed in every 10th percentile
- // Compute the rate limit for that percentile and sum it up
- for(int i=1;i<=10;i++){
- // Get the amount of time transactions take in the i*10th percentile
- double percentileTimeInNanos = timerSnapshot.getValue(i * 0.1D);
-
- if(percentileTimeInNanos > 0) {
- // Figure out the rate limit for the i*10th percentile in nanos
- double percentileRateLimit = (commitTimeoutInNanos / percentileTimeInNanos);
-
- // Add the percentileRateLimit to the total rate limit
- newRateLimit += percentileRateLimit;
- }
- }
-
- // Compute the rate limit per second
- return newRateLimit/(commitTimeoutInSeconds*10);
- }
-
- public static void adjustRateLimitForUnusedTransaction(ActorContext actorContext) {
- // Unused transactions in one data store can artificially limit the rate for other data stores
- // if the first data store's rate is still at a lower initial rate since the front-end creates
- // transactions in each data store up-front even though the client may not actually submit changes.
- // So we may have to adjust the rate for data stores with unused transactions.
-
- // First calculate the current rate for the data store. If it's 0 then there have been no
- // actual transactions committed to the data store.
-
- double newRateLimit = calculateNewRateLimit(actorContext.getOperationTimer(COMMIT),
- actorContext.getDatastoreContext());
- if(newRateLimit == 0.0) {
- // Since we have no rate data for unused Tx's data store, adjust to the rate from another
- // data store that does have rate data.
- for(String datastoreType: DatastoreContext.getGlobalDatastoreTypes()) {
- if(datastoreType.equals(actorContext.getDataStoreType())) {
- continue;
- }
-
- newRateLimit = calculateNewRateLimit(actorContext.getOperationTimer(datastoreType, COMMIT),
- actorContext.getDatastoreContext());
- if(newRateLimit > 0.0) {
- LOG.debug("On unused Tx - data Store {} commit rateLimit adjusted to {}",
- actorContext.getDataStoreType(), newRateLimit);
-
- actorContext.setTxCreationLimit(newRateLimit);
- break;
- }
- }
- }