When auto-compacting, the reftable library packs references such that
the sizes of the tables form a geometric sequence. The factor for this
geometric sequence is hardcoded to 2 right now. We're about to expose
this as a config option though, so let's expose the factor via write
options.
Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
---
reftable/constants.h | 1 +
reftable/reftable-writer.h | 6 ++++++
reftable/stack.c | 14 ++++++++++----
reftable/stack.h | 3 ++-
reftable/stack_test.c | 4 ++--
5 files changed, 21 insertions(+), 7 deletions(-)
diff --git a/reftable/constants.h b/reftable/constants.h
index 5eee72c4c1..f6beb843eb 100644
--- a/reftable/constants.h
+++ b/reftable/constants.h
@@ -17,5 +17,6 @@ license that can be found in the LICENSE file or at
#define MAX_RESTARTS ((1 << 16) - 1)
#define DEFAULT_BLOCK_SIZE 4096
+#define DEFAULT_GEOMETRIC_FACTOR 2
#endif
diff --git a/reftable/reftable-writer.h b/reftable/reftable-writer.h
index 94804eaa68..189b1f4144 100644
--- a/reftable/reftable-writer.h
+++ b/reftable/reftable-writer.h
@@ -45,6 +45,12 @@ struct reftable_write_options {
/* boolean: Prevent auto-compaction of tables. */
unsigned disable_auto_compact : 1;
+
+ /*
+ * Geometric sequence factor used by auto-compaction to decide which
+ * tables to compact. Defaults to 2 if unset.
+ */
+ uint8_t auto_compaction_factor;
};
/* reftable_block_stats holds statistics for a single block type */
diff --git a/reftable/stack.c b/reftable/stack.c
index d2e68be7e8..0ebe69e81d 100644
--- a/reftable/stack.c
+++ b/reftable/stack.c
@@ -10,6 +10,7 @@ license that can be found in the LICENSE file or at
#include "../write-or-die.h"
#include "system.h"
+#include "constants.h"
#include "merged.h"
#include "reader.h"
#include "reftable-error.h"
@@ -1212,12 +1213,16 @@ static int segment_size(struct segment *s)
return s->end - s->start;
}
-struct segment suggest_compaction_segment(uint64_t *sizes, size_t n)
+struct segment suggest_compaction_segment(uint64_t *sizes, size_t n,
+ uint8_t factor)
{
struct segment seg = { 0 };
uint64_t bytes;
size_t i;
+ if (!factor)
+ factor = DEFAULT_GEOMETRIC_FACTOR;
+
/*
* If there are no tables or only a single one then we don't have to
* compact anything. The sequence is geometric by definition already.
@@ -1249,7 +1254,7 @@ struct segment suggest_compaction_segment(uint64_t *sizes, size_t n)
* 64, 32, 16, 8, 4, 3, 1
*/
for (i = n - 1; i > 0; i--) {
- if (sizes[i - 1] < sizes[i] * 2) {
+ if (sizes[i - 1] < sizes[i] * factor) {
seg.end = i + 1;
bytes = sizes[i];
break;
@@ -1275,7 +1280,7 @@ struct segment suggest_compaction_segment(uint64_t *sizes, size_t n)
uint64_t curr = bytes;
bytes += sizes[i - 1];
- if (sizes[i - 1] < curr * 2) {
+ if (sizes[i - 1] < curr * factor) {
seg.start = i - 1;
seg.bytes = bytes;
}
@@ -1301,7 +1306,8 @@ int reftable_stack_auto_compact(struct reftable_stack *st)
{
uint64_t *sizes = stack_table_sizes_for_compaction(st);
struct segment seg =
- suggest_compaction_segment(sizes, st->merged->stack_len);
+ suggest_compaction_segment(sizes, st->merged->stack_len,
+ st->opts.auto_compaction_factor);
reftable_free(sizes);
if (segment_size(&seg) > 0)
return stack_compact_range_stats(st, seg.start, seg.end - 1,
diff --git a/reftable/stack.h b/reftable/stack.h
index 97d7ebc043..5b45cff4f7 100644
--- a/reftable/stack.h
+++ b/reftable/stack.h
@@ -35,6 +35,7 @@ struct segment {
uint64_t bytes;
};
-struct segment suggest_compaction_segment(uint64_t *sizes, size_t n);
+struct segment suggest_compaction_segment(uint64_t *sizes, size_t n,
+ uint8_t factor);
#endif
diff --git a/reftable/stack_test.c b/reftable/stack_test.c
index d15f11d712..0f7b1453e6 100644
--- a/reftable/stack_test.c
+++ b/reftable/stack_test.c
@@ -729,7 +729,7 @@ static void test_suggest_compaction_segment(void)
{
uint64_t sizes[] = { 512, 64, 17, 16, 9, 9, 9, 16, 2, 16 };
struct segment min =
- suggest_compaction_segment(sizes, ARRAY_SIZE(sizes));
+ suggest_compaction_segment(sizes, ARRAY_SIZE(sizes), 2);
EXPECT(min.start == 1);
EXPECT(min.end == 10);
}
@@ -738,7 +738,7 @@ static void test_suggest_compaction_segment_nothing(void)
{
uint64_t sizes[] = { 64, 32, 16, 8, 4, 2 };
struct segment result =
- suggest_compaction_segment(sizes, ARRAY_SIZE(sizes));
+ suggest_compaction_segment(sizes, ARRAY_SIZE(sizes), 2);
EXPECT(result.start == result.end);
}
--
2.45.GIT
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