cmccabe commented on code in PR #12595:
URL: https://github.com/apache/kafka/pull/12595#discussion_r966431199
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metadata/src/main/java/org/apache/kafka/controller/QuorumController.java:
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@@ -844,6 +855,72 @@ public String toString() {
}
}
+ /**
+ * Append records to the Raft log. They will be written out asynchronously.
+ *
+ * @param log The log4j logger.
+ * @param result The controller result we are writing out.
+ * @param maxRecordsPerBatch The maximum number of records to allow in
a batch.
+ * @param appender The callback to invoke for each batch. The
arguments are last
+ * write offset, record list, and the return
result is the new
+ * last write offset.
+ * @return The final offset that was returned from
the Raft layer.
+ */
+ static long appendRecords(
+ Logger log,
+ ControllerResult<?> result,
+ int maxRecordsPerBatch,
+ Function<List<ApiMessageAndVersion>, Long> appender
+ ) {
+ try {
+ List<ApiMessageAndVersion> records = result.records();
+ if (result.isAtomic()) {
+ // If the result must be written out atomically, check that it
is not too large.
+ // In general, we create atomic batches when it is important
to commit "all, or
+ // nothing". They are limited in size and must only be used
when the batch size
+ // is bounded.
+ if (records.size() > maxRecordsPerBatch) {
+ throw new IllegalStateException("Attempted to atomically
commit " +
+ records.size() + " records, but maxRecordsPerBatch
is " +
+ maxRecordsPerBatch);
+ }
+ long offset = appender.apply(records);
+ if (log.isTraceEnabled()) {
+ log.trace("Atomically appended {} record(s) ending with
offset {}.",
+ records.size(), offset);
+ }
+ return offset;
+ } else {
+ // If the result is non-atomic, then split it into as many
batches as needed.
+ // The appender callback will create an in-memory snapshot for
each batch,
+ // since we might need to revert to any of them. We will only
return the final
+ // offset of the last batch, however.
+ int i = 0, numBatches = 0;
+ while (true) {
+ numBatches++;
+ int j = i + maxRecordsPerBatch;
+ if (j > records.size()) {
+ long offset = appender.apply(records.subList(i,
records.size()));
Review Comment:
Yeah... In general LinkedList turns a lot of stuff into O(N) and that's why
we mostly don't use it. It's only really useful if you want to delete things
from the middle of a list in O(1), but you also don't need fast access to the
middle of the list, which is a pretty rare situation.
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