MB-67552: Recompute checkpoint's max size at checkpoint quota change

From MB-48038 where we introduced checkpoint_max_size:

  That is the maximum size (in bytes) for a single checkpoint.
  '0' triggers EP auto-setup, where the value is determined based on
  other system parameters (eg, num of vbuckets, checkpoint quota, max
  num of checkpoints per vbucket, etc..) for optimal balance and
  checkpoint memory releasing capabilities.

Change-Id: Id31106f372bd30ba52bf637e2c78b4872eb78b93
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/230483
Tested-by: Build Bot <[email protected]>
Reviewed-by: Vesko Karaganev <[email protected]>

Author: paolococchi

engines/ep/src/checkpoint_config.cc

@@ -48,6 +48,5 @@ void CheckpointConfig::setMaxCheckpoints(size_t value) {
 }
 
 void CheckpointConfig::setCheckpointMaxSize(size_t value) {
-    Expects(value >= 1);
     checkpointMaxSize = value;
 }

engines/ep/src/kv_bucket.cc

@@ -3078,6 +3078,11 @@ cb::engine_errc KVBucket::setCheckpointMemoryRatio(float ratio) {
         return cb::engine_errc::invalid_arguments;
     }
     checkpointMemoryRatio = ratio;
+
+    if (getConfiguration().getCheckpointMaxSize() == 0) {
+        autoConfigCheckpointMaxSize();
+    }
+
     return cb::engine_errc::success;
 }
 
@@ -3161,25 +3166,19 @@ cb::engine_errc KVBucket::autoConfigCheckpointMaxSize() {
     const auto numCheckpointsPerVB = config.getMaxCheckpoints();
 
     const auto checkpointQuota = maxSize * ckptMemRatio;
-    Expects(checkpointQuota > 0);
+    Expects(checkpointQuota >= 0);
 
     const size_t newComputedCheckpointMaxSize =
             checkpointQuota / numVBuckets / numCheckpointsPerVB;
-    if (newComputedCheckpointMaxSize < 1) {
-        throw std::invalid_argument(
-                fmt::format("KVBucket::autoConfigCheckpointMaxSize: "
-                            "newComputedCheckpointMaxSize:{} is < 1. "
-                            "max_size:{}, "
-                            "checkpoint mem ratio:{}, "
-                            "checkpoint quota:{}, "
-                            "numVBuckets:{}, "
-                            "numCheckpointsPerVB:{}",
-                            newComputedCheckpointMaxSize,
-                            maxSize,
-                            ckptMemRatio,
-                            checkpointQuota,
-                            numVBuckets,
-                            numCheckpointsPerVB));
+    if (newComputedCheckpointMaxSize == 0) {
+        EP_LOG_WARN_CTX(
+                "KVBucket::autoConfigCheckpointMaxSize: "
+                "newComputedCheckpointMaxSize is 0",
+                {"max_size", maxSize},
+                {"checkpoint_memory_ratio", ckptMemRatio},
+                {"checkpoint_quota", checkpointQuota},
+                {"num_vbuckets", numVBuckets},
+                {"num_checkpoints_per_vb", numCheckpointsPerVB});
     }
 
     const auto flushMaxBytes = config.getFlushBatchMaxBytes();

engines/ep/tests/module_tests/checkpoint_test.cc

@@ -1323,6 +1323,24 @@ TEST_F(SingleThreadedCheckpointTest, CheckpointMaxSize_CapAtFlushMaxBytes) {
     EXPECT_EQ(2_GiB, ckptConfig.getCheckpointMaxSize());
 }
 
+TEST_F(SingleThreadedCheckpointTest,
+       CheckpointMaxSize_RecomputeAtCheckpointQuotaChange) {
+    auto& config = engine->getConfiguration();
+    config.setMaxSize(1_GiB);
+    config.setCheckpointMemoryRatio(1.0f);
+    config.setMaxCheckpoints(2);
+
+    setVBucketState(vbid, vbucket_state_active);
+    auto vb = store->getVBuckets().getBucket(vbid);
+    auto& manager = *vb->checkpointManager;
+
+    const auto& ckptConfig = manager.getCheckpointConfig();
+    EXPECT_EQ(512_MiB, ckptConfig.getCheckpointMaxSize());
+
+    config.setCheckpointMemoryRatio(0.5f);
+    EXPECT_EQ(256_MiB, ckptConfig.getCheckpointMaxSize());
+}
+
 TEST_F(SingleThreadedCheckpointTest, MemUsageCheckpointCreation) {
     auto& config = engine->getConfiguration();
     config.setMaxSize(100_MiB);