From 4c2e16fee80d1f2370d37b67b06f0c09cfa8d66d Mon Sep 17 00:00:00 2001
From: Douglas Rumbaugh <dbr4@psu.edu>
Date: Mon, 8 May 2023 13:18:10 -0400
Subject: Ported PageFile.h over

---
 include/io/PagedFile.h | 434 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 434 insertions(+)
 create mode 100644 include/io/PagedFile.h

(limited to 'include')

diff --git a/include/io/PagedFile.h b/include/io/PagedFile.h
new file mode 100644
index 0000000..516c0d9
--- /dev/null
+++ b/include/io/PagedFile.h
@@ -0,0 +1,434 @@
+/*
+ * include/io/PagedFile.h
+ *
+ * Copyright (C) 2023 Douglas Rumbaugh <drumbaugh@psu.edu> 
+ *
+ * All rights reserved. Published under the Modified BSD License.
+ *
+ */
+#pragma once
+#define __GNU_SOURCE
+
+#include <string>
+#include <memory>
+#include <cassert>
+#include <vector>
+#include <algorithm>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <fcntl.h>
+
+#include "util/types.h"
+#include "util/base.h"
+
+#define PF_COUNT_IO
+
+#ifdef PF_COUNT_IO
+    #define INC_READ() de::pf_read_cnt++
+    #define INC_WRITE() de::pf_write_cnt++
+    #define RESET_IO_CNT() \
+        de::pf_read_cnt = 0; \
+        de::pf_write_cnt = 0
+#else
+    #define INC_READ() do {} while (0)
+    #define INC_WRITE() do {} while (0)
+    #define RESET_IO_CNT() do {} while (0)
+#endif
+
+namespace de {
+
+static thread_local size_t pf_read_cnt = 0;
+static thread_local size_t pf_write_cnt  = 0;
+
+class PagedFileIterator;
+class PagedFile;
+static PagedFileIterator *create_pfile_iter(PagedFile *pfile, PageNum start_page=0, PageNum stop_page=0);
+
+class PagedFile {
+public:
+    static PagedFile *create(const std::string fname, bool new_file=true) {
+        auto flags = O_RDWR;
+        mode_t mode = 0640;
+        off_t size = 0;
+
+        if (new_file) {
+            flags |= O_CREAT | O_TRUNC;
+        } 
+
+        int fd = open(fname.c_str(), flags, mode);
+        if (fd == -1) {
+            return nullptr;
+        }
+        
+        if (new_file) {
+            if(fallocate(fd, 0, 0, PAGE_SIZE)) {
+                return nullptr;
+            }
+
+            size = PAGE_SIZE;
+        } else {
+            struct stat buf;
+            if (fstat(fd, &buf) == -1) {
+                return nullptr;
+            }
+
+            size = buf.st_size;
+        } 
+
+        if (fd) {
+            return new PagedFile(fd, fname, size, mode);
+        }
+
+        return nullptr;
+
+    }
+
+    ~PagedFile() {
+        if (m_file_open) {
+            close(m_fd);
+        }
+    }
+
+    /*
+     * Add new_page_count new pages to the file in bulk, and returns the
+     * PageId of the first page in the new range.
+     *
+     * If the allocation fails, returns INVALID_PID. Also returns INVALID_PID
+     * if bulk allocation is not supported by the implementation. This can be
+     * iter1. checked via the supports_allocation method.
+     */
+    PageNum allocate_pages(PageNum count=1) {
+        PageNum new_first = get_page_count() + 1;
+        size_t alloc_size = count * PAGE_SIZE;
+
+        if (raw_allocate(alloc_size)) {
+            return new_first;
+        }
+
+        return INVALID_PNUM;
+    }
+
+    /*
+     * Reads data from the specified page into a buffer pointed to by
+     * buffer_ptr. It is necessary for buffer_ptr to be parm::SECTOR_SIZE
+     * aligned, and also for it to be large enough to accommodate
+     * parm::PAGE_SIZE chars. If the read succeeds, returns 1. Otherwise
+     * returns 0. The contents of the input buffer are undefined in the case of
+     * an error.
+     */
+    int read_page(PageNum pnum, char *buffer_ptr) {
+
+        return (check_pnum(pnum)) ? raw_read(buffer_ptr, PAGE_SIZE, PagedFile::pnum_to_offset(pnum))
+                                  : 0;
+    }
+
+    /*
+     * Reads several pages into associated buffers. It is necessary for the
+     * buffer referred to by each pointer to be parm::SECTOR_SIZE aligned and
+     * large enough to accommodate parm::PAGE_SIZE chars. If possible,
+     * vectorized IO may be used to read adjacent pages. If the reads succeed,
+     * returns 1. If a read fails, returns 0. The contents of all the buffers
+     * are undefined in the case of an error.
+     */
+    int read_pages(std::vector<std::pair<PageNum, char*>> pages) {
+        if (pages.size() == 0) {
+            return 0;
+        }
+
+        if (pages.size() == 1) {
+            read_page(pages[0].first, pages[0].second);
+        }
+
+        std::sort(pages.begin(), pages.end());
+
+        PageNum range_start = pages[0].first;
+        PageNum prev_pnum = range_start;
+
+        std::vector<char *> buffers;
+        buffers.push_back(pages[0].second);
+
+        for (size_t i=1; i<pages.size(); i++) {
+            if (pages[i].first == prev_pnum + 1) {
+                buffers.push_back(pages[i].second);
+                prev_pnum = pages[i].first;
+            } else {
+                if (!raw_readv(buffers, PAGE_SIZE, PagedFile::pnum_to_offset(range_start))) {
+                    return 0;
+                }
+
+                range_start = pages[i].first;
+                prev_pnum = range_start;
+
+                buffers.clear();
+                buffers.push_back(pages[i].second);
+            }
+        }
+
+        return raw_readv(buffers, PAGE_SIZE, PagedFile::pnum_to_offset(range_start));
+    }
+
+    /*
+     * Reads several pages stored contiguously into a single buffer. It is
+     * necessary that buffer_ptr be SECTOR_SIZE aligned and also at least 
+     * page_cnt * PAGE_SIZE chars large.
+     */
+    int read_pages(PageNum first_page, size_t page_cnt, char *buffer_ptr) {
+        if (check_pnum(first_page) && check_pnum(first_page + page_cnt - 1)) {
+            return raw_read(buffer_ptr, page_cnt * PAGE_SIZE, first_page * PAGE_SIZE); 
+        }
+
+        return 0;
+    }
+
+    /*
+     * Writes data from the provided buffer into the specified page within the
+     * file. It is necessary for buffer_ptr to be parm::SECTOR_SIZE aligned,
+     * and also for it to be at least parm::PAGE_SIZE chars large. If it is
+     * larger, only the first parm::PAGE_SIZE chars will be written. If it is
+     * smaller, the result is undefined.
+     *
+     * If the write succeeds, returns 1. Otherwise returns 0. The contents of
+     * the specified page within the file are undefined in the case of an error.
+     */
+    int write_page(PageNum pnum, const char *buffer_ptr) {
+        if (check_pnum(pnum)) {
+            return raw_write(buffer_ptr, PAGE_SIZE, PagedFile::pnum_to_offset(pnum));
+        }
+
+        return 0;
+    }
+
+    /*
+     * Writes multiple pages stored sequentially in the provided buffer into
+     * a contiguous region of the file, starting at first_page. If the write
+     * would overrun the allocated space in the file, no data is written.
+     *
+     * It is necessary for buffer_ptr to be SECTOR_SIZE aligned, and at 
+     * least PAGE_SIZE * page_cnt chars large.
+     *
+     * Returns the number of complete pages successfully written.
+     */
+    int write_pages(PageNum first_page, size_t page_cnt, const char *buffer_ptr) {
+        if (check_pnum(first_page) && check_pnum(first_page + page_cnt - 1)) {
+           return raw_write(buffer_ptr, page_cnt * PAGE_SIZE, first_page * PAGE_SIZE); 
+        }
+
+        return 0;
+    }
+
+    /*
+     * Returns the number of allocated paged in the file.
+     */
+    PageNum get_page_count() {
+        return m_size / PAGE_SIZE - 1;
+    }
+
+    /*
+     * Delete this file from the underlying filesystem. Once this has been called,
+     * this object will be closed, and all operations other than destructing it are
+     * undefined. Returns 1 on successful removal of the file, and 0 on failure.
+     */
+    int remove_file() {
+        if (m_file_open) {
+            close(m_fd);
+        }
+
+        if (unlink(m_fname.c_str())) {
+            return 0;
+        }
+
+        m_file_open = false;
+
+        return 1;
+    }
+
+    /*
+     * Returns the raw number of bytes allocated in the backing file.
+     */
+    off_t get_file_size() const {
+        return m_size;
+    }
+
+    PagedFileIterator *start_scan(PageNum start_page=1, PageNum end_page=0) {
+        if (end_page == INVALID_PNUM) {
+            end_page = get_page_count();
+        }
+
+        if (check_pnum(start_page) && check_pnum(end_page)) {
+            return create_pfile_iter(this, start_page, end_page);
+        }
+
+        return nullptr;
+    }
+
+    std::string get_fname() {
+        return m_fname;
+    }
+
+    void rename_file(std::string new_fname) {
+        if(rename(m_fname.c_str(), new_fname.c_str())) {
+            fprintf(stderr, "%s -> %s\n", m_fname.c_str(), new_fname.c_str());
+            perror("IN RENAME:");
+            assert(false);
+        }
+
+        m_fname = new_fname;
+    }
+
+private:
+    PagedFile(int fd, std::string fname, off_t size, mode_t mode) {
+        m_file_open = true;
+        m_fd = fd;
+        m_fname = fname;
+        m_size = size;
+        m_mode = mode;
+        m_flags = O_RDWR | O_DIRECT;
+    }
+
+    static off_t pnum_to_offset(PageNum pnum) {
+        return pnum * PAGE_SIZE;
+    }
+
+    bool check_pnum(PageNum pnum) const {
+        return pnum != INVALID_PNUM && pnum < (get_file_size() / PAGE_SIZE);
+    }
+
+    int raw_read(char *buffer, off_t amount, off_t offset) {
+        if (!verify_io_parms(amount, offset)) {
+            return 0;
+        }
+
+        if (pread(m_fd, buffer, amount, offset) != amount) {
+            return 0;
+        }
+
+        INC_READ();
+
+        return 1;
+    }
+
+    int raw_readv(std::vector<char *> buffers, off_t buffer_size, off_t initial_offset) {
+        size_t buffer_cnt = buffers.size();
+
+        off_t amount = buffer_size * buffer_cnt;
+        if (!verify_io_parms(amount, initial_offset)) {
+            return 0;
+        }
+
+        auto iov = new iovec[buffer_cnt];
+        for (size_t i=0; i<buffer_cnt; i++) {
+            iov[i].iov_base = buffers[i];
+            iov[i].iov_len = buffer_size;
+        }
+
+        if (preadv(m_fd, iov, buffer_cnt, initial_offset) != amount) {
+            return 0;
+        }
+
+        INC_READ();
+
+        delete[] iov;
+
+        return 1;
+    }
+
+    int raw_write(const char *buffer, off_t amount, off_t offset) {
+        if (!verify_io_parms(amount, offset)) {
+            return 0;
+        }
+
+        if (pwrite(m_fd, buffer, amount, offset) != amount) {
+            return 0;
+        }
+
+        INC_WRITE();
+
+        return 1;
+    }
+
+    int raw_allocate(size_t amount) {
+        if (!m_file_open || (amount % SECTOR_SIZE != 0)) {
+            return 0;
+        }
+
+        int alloc_mode = 0;
+        if (fallocate(m_fd, alloc_mode, m_size, amount)) {
+            return 0;
+        }
+
+        m_size += amount;
+        return 1;
+    }
+
+    bool verify_io_parms(off_t amount, off_t offset) {
+        if (!m_file_open || amount + offset > m_size) {
+            return false;
+        }
+
+        if (amount % SECTOR_SIZE != 0) {
+            return false;
+        }
+
+        if (offset % SECTOR_SIZE != 0) {
+            return false;
+        }
+
+        return true;
+    }
+
+    int m_fd;
+    bool m_file_open;
+    off_t m_size;
+    mode_t m_mode;
+    std::string m_fname;
+    int m_flags;
+};
+
+
+class PagedFileIterator {
+public:
+  PagedFileIterator(PagedFile *pfile, PageNum start_page = 0,
+                    PageNum stop_page = 0)
+      : m_pfile(pfile),
+        m_current_pnum((start_page == INVALID_PNUM) ? 0 : start_page - 1),
+        m_start_pnum(start_page), m_stop_pnum(stop_page),
+        m_buffer((char *)aligned_alloc(SECTOR_SIZE, PAGE_SIZE)) {}
+
+  bool next() {
+    while (m_current_pnum < m_stop_pnum) {
+      if (m_pfile->read_page(++m_current_pnum, m_buffer)) {
+        return true;
+      }
+
+      // IO error of some kind
+      return false;
+    }
+
+    // no more pages to read
+    return false;
+    }
+
+    char *get_item() {
+        return m_buffer;
+    }
+
+    ~PagedFileIterator() {
+        free(m_buffer);
+    }
+
+private:
+    PagedFile *m_pfile;
+    PageNum m_current_pnum;
+    PageNum m_start_pnum;
+    PageNum m_stop_pnum;
+
+    char *m_buffer;
+};
+
+static PagedFileIterator *create_pfile_iter(PagedFile *pfile, PageNum start_page, PageNum stop_page) {
+    return new PagedFileIterator(pfile, start_page, stop_page);
+}
+
+}
-- 
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