Merge pull request #39974 from ClickHouse/vdimir/setting-num-with-auto

Add setting type to support special 'auto' value

src/Core/Settings.h

@@ -212,7 +212,7 @@ static constexpr UInt64 operator""_GiB(unsigned long long value)
     \
     M(Bool, insert_deduplicate, true, "For INSERT queries in the replicated table, specifies that deduplication of insertings blocks should be performed", 0) \
     \
-    M(UInt64, insert_quorum, 0, "For INSERT queries in the replicated table, wait writing for the specified number of replicas and linearize the addition of the data. 0 - disabled.", 0) \
+    M(UInt64Auto, insert_quorum, 0, "For INSERT queries in the replicated table, wait writing for the specified number of replicas and linearize the addition of the data. 0 - disabled.", 0) \
     M(Milliseconds, insert_quorum_timeout, 600000, "", 0) \
     M(Bool, insert_quorum_parallel, true, "For quorum INSERT queries - enable to make parallel inserts without linearizability", 0) \
     M(UInt64, select_sequential_consistency, 0, "For SELECT queries from the replicated table, throw an exception if the replica does not have a chunk written with the quorum; do not read the parts that have not yet been written with the quorum.", 0) \

src/Core/SettingsFields.cpp

@@ -153,6 +153,9 @@ template struct SettingFieldNumber<Int64>;
 template struct SettingFieldNumber<float>;
 template struct SettingFieldNumber<bool>;
 
+template struct SettingAutoWrapper<SettingFieldNumber<UInt64>>;
+template struct SettingAutoWrapper<SettingFieldNumber<Int64>>;
+template struct SettingAutoWrapper<SettingFieldNumber<float>>;
 
 namespace
 {

src/Core/SettingsFields.h

@@ -58,11 +58,82 @@ using SettingFieldInt64 = SettingFieldNumber<Int64>;
 using SettingFieldFloat = SettingFieldNumber<float>;
 using SettingFieldBool = SettingFieldNumber<bool>;
 
-
+/** Wraps any SettingField to support special value 'auto' that can be checked with `is_auto` flag.
-/** Unlike SettingFieldUInt64, supports the value of 'auto' - the number of processor cores without taking into account SMT.
+  * Note about serialization:
-  * A value of 0 is also treated as auto.
+  * The new versions with `SettingsWriteFormat::STRINGS_WITH_FLAGS` serialize values as a string.
-  * When serializing, `auto` is written in the same way as 0.
+  * In legacy SettingsWriteFormat mode, functions `read/writeBinary` would serialize values as a binary, and 'is_auto' would be ignored.
+  * It's possible to upgrade settings from regular type to wrapped ones and keep compatibility with old versions,
+  * but when serializing 'auto' old version will see binary representation of the default value.
   */
+template <typename Base>
+struct SettingAutoWrapper
+{
+    constexpr static auto keyword = "auto";
+    static bool isAuto(const Field & f) { return f.getType() == Field::Types::String && f.safeGet<const String &>() == keyword; }
+    static bool isAuto(const String & str) { return str == keyword; }
+
+    using Type = typename Base::Type;
+
+    Base base;
+    bool is_auto = false;
+    bool changed = false;
+
+    explicit SettingAutoWrapper() : is_auto(true) {}
+    explicit SettingAutoWrapper(Type val) : is_auto(false) { base = Base(val); }
+
+    explicit SettingAutoWrapper(const Field & f)
+        : is_auto(isAuto(f))
+    {
+        if (!is_auto)
+            base = Base(f);
+    }
+
+    SettingAutoWrapper & operator=(const Field & f)
+    {
+        changed = true;
+        if (is_auto = isAuto(f); !is_auto)
+            base = f;
+        return *this;
+    }
+
+    explicit operator Field() const { return is_auto ? Field(keyword) : Field(base); }
+
+    String toString() const { return is_auto ? keyword : base.toString(); }
+
+    void parseFromString(const String & str)
+    {
+        changed = true;
+        if (is_auto = isAuto(str); !is_auto)
+            base.parseFromString(str);
+    }
+
+    void writeBinary(WriteBuffer & out) const
+    {
+        if (is_auto)
+            Base().writeBinary(out); /// serialize default value
+        else
+            base.writeBinary(out);
+    }
+
+    /*
+     * That it is fine to reset `is_auto` here and to use default value in case `is_auto`
+     * because settings will be serialized only if changed.
+     * If they were changed they were requested to use explicit value instead of `auto`.
+     * And so interactions between client-server, and server-server (distributed queries), should be OK.
+     */
+    void readBinary(ReadBuffer & in) { changed = true; is_auto = false; base.readBinary(in); }
+
+    Type valueOr(Type default_value) const { return is_auto ? default_value : base.value; }
+};
+
+using SettingFieldUInt64Auto = SettingAutoWrapper<SettingFieldUInt64>;
+using SettingFieldInt64Auto = SettingAutoWrapper<SettingFieldInt64>;
+using SettingFieldFloatAuto = SettingAutoWrapper<SettingFieldFloat>;
+
+/* Similar to SettingFieldUInt64Auto with small differences to behave like regular UInt64, supported to compatibility.
+ * When setting to 'auto' it becomes equal to  the number of processor cores without taking into account SMT.
+ * A value of 0 is also treated as 'auto', so 'auto' is parsed and serialized in the same way as 0.
+ */
 struct SettingFieldMaxThreads
 {
     bool is_auto;

src/Storages/StorageReplicatedMergeTree.cpp

@@ -4443,8 +4443,9 @@ SinkToStoragePtr StorageReplicatedMergeTree::write(const ASTPtr & /*query*/, con
     bool deduplicate = storage_settings_ptr->replicated_deduplication_window != 0 && query_settings.insert_deduplicate;
 
     // TODO: should we also somehow pass list of columns to deduplicate on to the ReplicatedMergeTreeSink?
+    // TODO: insert_quorum = 'auto' would be supported in https://github.com/ClickHouse/ClickHouse/pull/39970, now it's same as 0.
     return std::make_shared<ReplicatedMergeTreeSink>(
-        *this, metadata_snapshot, query_settings.insert_quorum,
+        *this, metadata_snapshot, query_settings.insert_quorum.valueOr(0),
         query_settings.insert_quorum_timeout.totalMilliseconds(),
         query_settings.max_partitions_per_insert_block,
         query_settings.insert_quorum_parallel,

tests/queries/0_stateless/02381_setting_value_auto.reference

@@ -0,0 +1,4 @@
+0	0	UInt64Auto
+auto	1	UInt64Auto
+0	1	UInt64Auto
+1	1	UInt64Auto

tests/queries/0_stateless/02381_setting_value_auto.sql

@@ -0,0 +1,10 @@
+SELECT value, changed, type FROM system.settings WHERE name = 'insert_quorum';
+
+SET insert_quorum = 'auto';
+SELECT value, changed, type FROM system.settings WHERE name = 'insert_quorum';
+
+SET insert_quorum = 0;
+SELECT value, changed, type FROM system.settings WHERE name = 'insert_quorum';
+
+SET insert_quorum = 1;
+SELECT value, changed, type FROM system.settings WHERE name = 'insert_quorum';