mirror of
https://github.com/ClickHouse/ClickHouse.git
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102 lines
2.3 KiB
C++
102 lines
2.3 KiB
C++
#include <sys/mman.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <Common/formatReadable.h>
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#include <Common/Exception.h>
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#include <base/getPageSize.h>
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#include <IO/MMappedFileDescriptor.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int CANNOT_ALLOCATE_MEMORY;
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extern const int CANNOT_MUNMAP;
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extern const int CANNOT_STAT;
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extern const int BAD_ARGUMENTS;
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extern const int LOGICAL_ERROR;
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}
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static size_t getFileSize(int fd)
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{
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struct stat stat_res {};
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if (0 != fstat(fd, &stat_res))
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throw ErrnoException(ErrorCodes::CANNOT_STAT, "MMappedFileDescriptor: Cannot fstat");
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off_t file_size = stat_res.st_size;
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if (file_size < 0)
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throw Exception(ErrorCodes::LOGICAL_ERROR, "MMappedFileDescriptor: fstat returned negative file size");
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return file_size;
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}
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MMappedFileDescriptor::MMappedFileDescriptor(int fd_, size_t offset_, size_t length_)
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{
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set(fd_, offset_, length_);
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}
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MMappedFileDescriptor::MMappedFileDescriptor(int fd_, size_t offset_)
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: fd(fd_), offset(offset_)
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{
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set(fd_, offset_);
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}
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void MMappedFileDescriptor::set(int fd_, size_t offset_, size_t length_)
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{
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finish();
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fd = fd_;
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offset = offset_;
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length = length_;
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if (!length)
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return;
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void * buf = mmap(nullptr, length, PROT_READ, MAP_PRIVATE, fd, offset);
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if (MAP_FAILED == buf)
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throw ErrnoException(ErrorCodes::CANNOT_ALLOCATE_MEMORY, "MMappedFileDescriptor: Cannot mmap {}", ReadableSize(length));
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data = static_cast<char *>(buf);
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files_metric_increment.changeTo(1);
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bytes_metric_increment.changeTo(length);
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}
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void MMappedFileDescriptor::set(int fd_, size_t offset_)
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{
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size_t file_size = getFileSize(fd_);
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if (offset > file_size)
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throw Exception(ErrorCodes::BAD_ARGUMENTS, "MMappedFileDescriptor: requested offset is greater than file size");
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set(fd_, offset_, file_size - offset);
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}
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void MMappedFileDescriptor::finish()
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{
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if (!length)
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return;
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if (0 != munmap(data, length))
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throw ErrnoException(ErrorCodes::CANNOT_MUNMAP, "MMappedFileDescriptor: Cannot munmap {}", ReadableSize(length));
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length = 0;
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files_metric_increment.changeTo(0);
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bytes_metric_increment.changeTo(0);
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}
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MMappedFileDescriptor::~MMappedFileDescriptor()
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{
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finish(); /// Exceptions will lead to std::terminate and that's Ok.
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}
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}
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