Clarify CompactionFilter thread safety requirements

Summary: Documenting our discussion

Test Plan: make

Reviewers: dhruba, haobo

Reviewed By: dhruba

CC: igor

Differential Revision: https://reviews.facebook.net/D14403
main
lovro 11 years ago
parent 0b5b81a154
commit 930cb0b9ee
  1. 10
      include/rocksdb/compaction_filter.h
  2. 28
      include/rocksdb/options.h
  3. 6
      util/options.cc

@ -40,6 +40,16 @@ class CompactionFilter {
// When the value is to be preserved, the application has the option
// to modify the existing_value and pass it back through new_value.
// value_changed needs to be set to true in this case.
//
// If multithreaded compaction is being used *and* a single CompactionFilter
// instance was supplied via Options::compaction_filter, this method may be
// called from different threads concurrently. The application must ensure
// that the call is thread-safe.
//
// If the CompactionFilter was created by a factory, then it will only ever
// be used by a single thread that is doing the compaction run, and this
// call does not need to be thread-safe. However, multiple filters may be
// in existence and operating concurrently.
virtual bool Filter(int level,
const Slice& key,
const Slice& existing_value,

@ -93,16 +93,33 @@ struct Options {
// Default: nullptr
shared_ptr<MergeOperator> merge_operator;
// The client must provide compaction_filter_factory if it requires a new
// compaction filter to be used for different compaction processes
// A single CompactionFilter instance to call into during compaction.
// Allows an application to modify/delete a key-value during background
// compaction.
// Ideally, client should specify only one of filter or factory.
//
// If the client requires a new compaction filter to be used for different
// compaction runs, it can specify compaction_filter_factory instead of this
// option. The client should specify only one of the two.
// compaction_filter takes precedence over compaction_filter_factory if
// client specifies both.
//
// If multithreaded compaction is being used, the supplied CompactionFilter
// instance may be used from different threads concurrently and so should be
// thread-safe.
//
// Default: nullptr
const CompactionFilter* compaction_filter;
// This is a factory that provides compaction filter objects which allow
// an application to modify/delete a key-value during background compaction.
//
// A new filter will be created on each compaction run. If multithreaded
// compaction is being used, each created CompactionFilter will only be used
// from a single thread and so does not need to be thread-safe.
//
// Default: a factory that doesn't provide any object
std::shared_ptr<CompactionFilterFactory> compaction_filter_factory;
// If true, the database will be created if it is missing.
// Default: false
bool create_if_missing;
@ -600,11 +617,6 @@ struct Options {
// Table and TableBuilder.
std::shared_ptr<TableFactory> table_factory;
// This is a factory that provides compaction filter objects which allow
// an application to modify/delete a key-value during background compaction.
// Default: a factory that doesn't provide any object
std::shared_ptr<CompactionFilterFactory> compaction_filter_factory;
// This option allows user to to collect their own interested statistics of
// the tables.
// Default: emtpy vector -- no user-defined statistics collection will be

@ -25,6 +25,9 @@ Options::Options()
: comparator(BytewiseComparator()),
merge_operator(nullptr),
compaction_filter(nullptr),
compaction_filter_factory(
std::shared_ptr<CompactionFilterFactory>(
new DefaultCompactionFilterFactory())),
create_if_missing(false),
error_if_exists(false),
paranoid_checks(false),
@ -97,9 +100,6 @@ Options::Options()
memtable_factory(std::shared_ptr<SkipListFactory>(new SkipListFactory)),
table_factory(
std::shared_ptr<TableFactory>(new BlockBasedTableFactory())),
compaction_filter_factory(
std::shared_ptr<CompactionFilterFactory>(
new DefaultCompactionFilterFactory())),
inplace_update_support(false),
inplace_update_num_locks(10000) {
assert(memtable_factory.get() != nullptr);

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