mirror of
https://github.com/ClickHouse/ClickHouse.git
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129 lines
3.6 KiB
C++
129 lines
3.6 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/ProfileEvents.h>
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#include <Common/formatReadable.h>
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#include <Common/Exception.h>
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#include <IO/WriteHelpers.h>
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#include <IO/MMapReadBufferFromFileDescriptor.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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extern const int ARGUMENT_OUT_OF_BOUND;
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extern const int CANNOT_SEEK_THROUGH_FILE;
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}
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void MMapReadBufferFromFileDescriptor::init(int fd_, size_t offset, size_t length_)
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{
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fd = fd_;
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length = length_;
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if (length)
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{
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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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throwFromErrno("MMapReadBufferFromFileDescriptor: Cannot mmap " + formatReadableSizeWithBinarySuffix(length) + ".",
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ErrorCodes::CANNOT_ALLOCATE_MEMORY);
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BufferBase::set(static_cast<char *>(buf), length, 0);
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ReadBuffer::padded = (length % 4096) > 0 && (length % 4096) <= (4096 - 15); /// TODO determine page size
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}
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}
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void MMapReadBufferFromFileDescriptor::init(int fd_, size_t offset)
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{
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fd = fd_;
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struct stat stat_res {};
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if (0 != fstat(fd, &stat_res))
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throwFromErrno("MMapReadBufferFromFileDescriptor: Cannot fstat.", ErrorCodes::CANNOT_STAT);
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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("MMapReadBufferFromFileDescriptor: fstat returned negative file size", ErrorCodes::LOGICAL_ERROR);
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if (offset > static_cast<size_t>(file_size))
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throw Exception("MMapReadBufferFromFileDescriptor: requested offset is greater than file size", ErrorCodes::BAD_ARGUMENTS);
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init(fd, offset, file_size - offset);
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}
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MMapReadBufferFromFileDescriptor::MMapReadBufferFromFileDescriptor(int fd_, size_t offset_, size_t length_)
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{
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init(fd_, offset_, length_);
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}
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MMapReadBufferFromFileDescriptor::MMapReadBufferFromFileDescriptor(int fd_, size_t offset_)
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{
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init(fd_, offset_);
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}
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MMapReadBufferFromFileDescriptor::~MMapReadBufferFromFileDescriptor()
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{
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if (length)
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finish(); /// Exceptions will lead to std::terminate and that's Ok.
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}
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void MMapReadBufferFromFileDescriptor::finish()
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{
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if (0 != munmap(internalBuffer().begin(), length))
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throwFromErrno("MMapReadBufferFromFileDescriptor: Cannot munmap " + formatReadableSizeWithBinarySuffix(length) + ".",
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ErrorCodes::CANNOT_MUNMAP);
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length = 0;
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}
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std::string MMapReadBufferFromFileDescriptor::getFileName() const
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{
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return "(fd = " + toString(fd) + ")";
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}
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int MMapReadBufferFromFileDescriptor::getFD() const
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{
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return fd;
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}
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off_t MMapReadBufferFromFileDescriptor::getPosition()
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{
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return count();
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}
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off_t MMapReadBufferFromFileDescriptor::seek(off_t offset, int whence)
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{
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off_t new_pos;
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if (whence == SEEK_SET)
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new_pos = offset;
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else if (whence == SEEK_CUR)
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new_pos = count() + offset;
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else
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throw Exception("MMapReadBufferFromFileDescriptor::seek expects SEEK_SET or SEEK_CUR as whence", ErrorCodes::ARGUMENT_OUT_OF_BOUND);
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working_buffer = internal_buffer;
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if (new_pos < 0 || new_pos > off_t(working_buffer.size()))
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throw Exception("Cannot seek through file " + getFileName()
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+ " because seek position (" + toString(new_pos) + ") is out of bounds [0, " + toString(working_buffer.size()) + "]",
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ErrorCodes::CANNOT_SEEK_THROUGH_FILE);
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position() = working_buffer.begin() + new_pos;
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return new_pos;
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}
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}
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