github.com/zuoyebang/bitalosdb@v1.1.1-0.20240516111551-79a8c4d8ce20/internal/manual/manual.go (about)

     1  // Copyright 2021 The Bitalosdb author(hustxrb@163.com) and other contributors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package manual
    16  
    17  // #include <stdlib.h>
    18  import "C"
    19  import "unsafe"
    20  
    21  // The go:linkname directives provides backdoor access to private functions in
    22  // the runtime. Below we're accessing the throw function.
    23  
    24  //go:linkname throw runtime.throw
    25  func throw(s string)
    26  
    27  func New(n int) []byte {
    28  	if n == 0 {
    29  		return make([]byte, 0)
    30  	}
    31  
    32  	ptr := C.calloc(C.size_t(n), 1)
    33  	if ptr == nil {
    34  		throw("out of memory")
    35  	}
    36  
    37  	return (*[MaxArrayLen]byte)(unsafe.Pointer(ptr))[:n:n]
    38  }
    39  
    40  func Free(b []byte) {
    41  	if cap(b) != 0 {
    42  		if len(b) == 0 {
    43  			b = b[:cap(b)]
    44  		}
    45  		ptr := unsafe.Pointer(&b[0])
    46  		C.free(ptr)
    47  	}
    48  }