From: Zengran Zhang <zhangzengran@sangfor.com.cn>
Date: Tue, 2 Apr 2019 14:03:45 +0000 (+0800)
Subject: kv: make delete range optional on number of keys
X-Git-Tag: v15.1.0~3021^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=b039e63c6816ed371c6db975b4cbc7a3d170bb1f;p=ceph.git

kv: make delete range optional on number of keys

Actually, we may only wanna let the objects with real big number of omap to
use delete range. if not, we find too many tombstones will have side-effects
on performance of kv.

refer: https://github.com/facebook/rocksdb/wiki/DeleteRange-Implementation

Signed-off-by: Zengran Zhang <zhangzengran@sangfor.com.cn>
---

diff --git a/src/common/options.cc b/src/common/options.cc
index 268f496d8f2e..d5ecc21c1604 100644
--- a/src/common/options.cc
+++ b/src/common/options.cc
@@ -3789,7 +3789,12 @@ std::vector<Option> get_global_options() {
 
     Option("rocksdb_enable_rmrange", Option::TYPE_BOOL, Option::LEVEL_ADVANCED)
     .set_default(false)
-    .set_description(""),
+    .set_description("Refer to github.com/facebook/rocksdb/wiki/DeleteRange-Implementation"),
+
+    Option("rocksdb_max_items_rmrange", Option::TYPE_UINT, Option::LEVEL_ADVANCED)
+    .set_default(1024)
+    .set_description("Delete Range will be called if number of keys exceeded, must enable rocksdb_enable_rmrange first")
+    .add_see_also("rocksdb_enable_rmrange"),
 
     Option("rocksdb_bloom_bits_per_key", Option::TYPE_UINT, Option::LEVEL_ADVANCED)
     .set_default(20)
diff --git a/src/kv/RocksDBStore.cc b/src/kv/RocksDBStore.cc
index f056d8c2abce..4756697f270c 100644
--- a/src/kv/RocksDBStore.cc
+++ b/src/kv/RocksDBStore.cc
@@ -946,7 +946,25 @@ void RocksDBStore::RocksDBTransactionImpl::rmkeys_by_prefix(const string &prefix
   if (cf) {
     if (db->enable_rmrange) {
       string endprefix("\xff\xff\xff\xff");  // FIXME: this is cheating...
-      bat.DeleteRange(cf, string(), endprefix);
+      if (db->max_items_rmrange) {
+        uint64_t cnt = db->max_items_rmrange;
+        bat.SetSavePoint();
+        auto it = db->get_iterator(prefix);
+        for (it->seek_to_first();
+        it->valid();
+        it->next()) {
+          if (!cnt) {
+            bat.RollbackToSavePoint();
+            bat.DeleteRange(cf, string(), endprefix);
+            return;
+          }
+          bat.Delete(cf, rocksdb::Slice(it->key()));
+          --cnt;
+        }
+        bat.PopSavePoint();
+      } else {
+        bat.DeleteRange(cf, string(), endprefix);
+      }
     } else {
       auto it = db->get_iterator(prefix);
       for (it->seek_to_first();
@@ -959,9 +977,29 @@ void RocksDBStore::RocksDBTransactionImpl::rmkeys_by_prefix(const string &prefix
     if (db->enable_rmrange) {
       string endprefix = prefix;
       endprefix.push_back('\x01');
-      bat.DeleteRange(db->default_cf,
-		      combine_strings(prefix, string()),
-		      combine_strings(endprefix, string()));
+      if (db->max_items_rmrange) {
+        uint64_t cnt = db->max_items_rmrange;
+        bat.SetSavePoint();
+        auto it = db->get_iterator(prefix);
+        for (it->seek_to_first();
+             it->valid();
+             it->next()) {
+          if (!cnt) {
+            bat.RollbackToSavePoint();
+            bat.DeleteRange(db->default_cf,
+                combine_strings(prefix, string()),
+                combine_strings(endprefix, string()));
+            return;
+          }
+          bat.Delete(db->default_cf, combine_strings(prefix, it->key()));
+          --cnt;
+        }
+        bat.PopSavePoint();
+      } else {
+        bat.DeleteRange(db->default_cf,
+            combine_strings(prefix, string()),
+            combine_strings(endprefix, string()));
+      }
     } else {
       auto it = db->get_iterator(prefix);
       for (it->seek_to_first();
@@ -980,7 +1018,28 @@ void RocksDBStore::RocksDBTransactionImpl::rm_range_keys(const string &prefix,
   auto cf = db->get_cf_handle(prefix);
   if (cf) {
     if (db->enable_rmrange) {
-      bat.DeleteRange(cf, rocksdb::Slice(start), rocksdb::Slice(end));
+      if (db->max_items_rmrange) {
+        uint64_t cnt = db->max_items_rmrange;
+        auto it = db->get_iterator(prefix);
+        bat.SetSavePoint();
+        it->lower_bound(start);
+        while (it->valid()) {
+          if (it->key() >= end) {
+            break;
+          }
+          if (!cnt) {
+            bat.RollbackToSavePoint();
+            bat.DeleteRange(cf, rocksdb::Slice(start), rocksdb::Slice(end));
+            return;
+          }
+          bat.Delete(cf, rocksdb::Slice(it->key()));
+          it->next();
+          --cnt;
+        }
+        bat.PopSavePoint();
+      } else {
+        bat.DeleteRange(cf, rocksdb::Slice(start), rocksdb::Slice(end));
+      }
     } else {
       auto it = db->get_iterator(prefix);
       it->lower_bound(start);
@@ -994,10 +1053,35 @@ void RocksDBStore::RocksDBTransactionImpl::rm_range_keys(const string &prefix,
     }
   } else {
     if (db->enable_rmrange) {
-      bat.DeleteRange(
-	db->default_cf,
-	rocksdb::Slice(combine_strings(prefix, start)),
-	rocksdb::Slice(combine_strings(prefix, end)));
+      if (db->max_items_rmrange) {
+        uint64_t cnt = db->max_items_rmrange;
+        auto it = db->get_iterator(prefix);
+        bat.SetSavePoint();
+        it->lower_bound(start);
+        while (it->valid()) {
+          if (it->key() >= end) {
+            break;
+          }
+          if (!cnt) {
+            bat.RollbackToSavePoint();
+            bat.DeleteRange(
+                db->default_cf,
+                rocksdb::Slice(combine_strings(prefix, start)),
+                rocksdb::Slice(combine_strings(prefix, end)));
+            return;
+          }
+          bat.Delete(db->default_cf,
+          combine_strings(prefix, it->key()));
+          it->next();
+          --cnt;
+        }
+        bat.PopSavePoint();
+      } else {
+        bat.DeleteRange(
+            db->default_cf,
+            rocksdb::Slice(combine_strings(prefix, start)),
+            rocksdb::Slice(combine_strings(prefix, end)));
+      }
     } else {
       auto it = db->get_iterator(prefix);
       it->lower_bound(start);
diff --git a/src/kv/RocksDBStore.h b/src/kv/RocksDBStore.h
index 393853d16c0a..ea7c77d3c767 100644
--- a/src/kv/RocksDBStore.h
+++ b/src/kv/RocksDBStore.h
@@ -120,6 +120,7 @@ public:
   bool compact_on_mount;
   bool disableWAL;
   bool enable_rmrange;
+  const uint64_t max_items_rmrange;
   void compact() override;
 
   void compact_async() override {
@@ -159,7 +160,8 @@ public:
     compact_thread(this),
     compact_on_mount(false),
     disableWAL(false),
-    enable_rmrange(cct->_conf->rocksdb_enable_rmrange)
+    enable_rmrange(cct->_conf->rocksdb_enable_rmrange),
+    max_items_rmrange(cct->_conf.get_val<uint64_t>("rocksdb_max_items_rmrange"))
   {}
 
   ~RocksDBStore() override;