Encapsulate HLL logic (#1756)

be/src/exprs/hll_function.cpp

@@ -0,0 +1,110 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include "exprs/hll_function.h"
+
+#include "exprs/anyval_util.h"
+#include "util/hash_util.hpp"
+
+namespace doris {
+
+using doris_udf::BigIntVal;
+using doris_udf::StringVal;
+
+void HllFunctions::init() {
+}
+
+StringVal HllFunctions::hll_hash(FunctionContext* ctx, const StringVal& input) {
+    const int HLL_SINGLE_VALUE_SIZE = 10;
+    const int HLL_EMPTY_SIZE = 1;
+    std::string buf;
+    std::unique_ptr<HyperLogLog> hll;
+    if (!input.is_null) {
+        uint64_t hash_value = HashUtil::murmur_hash64A(input.ptr, input.len, HashUtil::MURMUR_SEED);
+        hll.reset(new HyperLogLog(hash_value));
+        buf.resize(HLL_SINGLE_VALUE_SIZE);
+    } else {
+        hll.reset(new HyperLogLog());
+        buf.resize(HLL_EMPTY_SIZE);
+    }
+    hll->serialize((char*)buf.c_str());
+    return AnyValUtil::from_string_temp(ctx, buf);
+}
+
+void HllFunctions::hll_init(FunctionContext *, StringVal* dst) {
+    dst->is_null = false;
+    dst->len = sizeof(HyperLogLog);
+    dst->ptr = (uint8_t*)new HyperLogLog();
+}
+
+template <typename T>
+void HllFunctions::hll_update(FunctionContext *, const T &src, StringVal* dst) {
+    if (src.is_null) {
+        return;
+    }
+
+    uint64_t hash_value = AnyValUtil::hash64_murmur(src, HashUtil::MURMUR_SEED);
+    if (hash_value != 0) {
+        auto* dst_hll = reinterpret_cast<HyperLogLog*>(dst->ptr);
+        dst_hll->update(hash_value);
+    }
+}
+void HllFunctions::hll_merge(FunctionContext*, const StringVal &src, StringVal* dst) {
+    HyperLogLog src_hll = HyperLogLog((char*)src.ptr);
+    auto* dst_hll = reinterpret_cast<HyperLogLog*>(dst->ptr);
+    dst_hll->merge(src_hll);
+}
+
+BigIntVal HllFunctions::hll_finalize(FunctionContext*, const StringVal &src) {
+    auto* src_hll = reinterpret_cast<HyperLogLog*>(src.ptr);
+    BigIntVal result(src_hll->estimate_cardinality());
+    delete src_hll;
+    return result;
+}
+
+BigIntVal HllFunctions::hll_cardinality(FunctionContext* ctx, const StringVal& input) {
+    if (input.is_null) {
+        return BigIntVal::null();
+    }
+    StringVal dst;
+    hll_init(ctx, &dst);
+    hll_merge(ctx, input, &dst);
+    return hll_finalize(ctx, dst);
+}
+
+StringVal HllFunctions::hll_serialize(FunctionContext *ctx, const StringVal &src) {
+    auto* src_hll = reinterpret_cast<HyperLogLog*>(src.ptr);
+    StringVal result(ctx, HLL_COLUMN_DEFAULT_LEN);
+    int size = src_hll->serialize((char*)result.ptr);
+    result.resize(ctx, size);
+    delete src_hll;
+    return result;
+}
+
+template void HllFunctions::hll_update(FunctionContext*, const BooleanVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const TinyIntVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const SmallIntVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const IntVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const BigIntVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const FloatVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const DoubleVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const StringVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const DateTimeVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const LargeIntVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const DecimalVal&, StringVal*);
+template void HllFunctions::hll_update(FunctionContext*, const DecimalV2Val&, StringVal*);
+}