/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
#ident "$Id$"
/*======
This file is part of PerconaFT.


Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.

    PerconaFT is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2,
    as published by the Free Software Foundation.

    PerconaFT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.

----------------------------------------

    PerconaFT is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License, version 3,
    as published by the Free Software Foundation.

    PerconaFT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
======= */

#ident "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."

#include "log-internal.h"
#include "logger/logcursor.h"
#include <limits.h>
#include <unistd.h>

enum lc_direction { LC_FORWARD, LC_BACKWARD, LC_FIRST, LC_LAST };

struct toku_logcursor {
    char *logdir;         // absolute directory name
    char **logfiles;
    int n_logfiles;
    int cur_logfiles_index;
    FILE *cur_fp;
    size_t buffer_size;
    void *buffer;
    bool is_open;
    struct log_entry entry;
    bool entry_valid;
    LSN cur_lsn;
    enum lc_direction last_direction;
};

#define LC_LSN_ERROR (DB_RUNRECOVERY)

void toku_logcursor_print(TOKULOGCURSOR lc)  {
    printf("lc = %p\n", lc);
    printf("  logdir = %s\n", lc->logdir);
    printf("  logfiles = %p\n", lc->logfiles);
    for (int lf=0;lf<lc->n_logfiles;lf++) {
        printf("    logfile[%d] = %p (%s)\n", lf, lc->logfiles[lf], lc->logfiles[lf]);
    }
    printf("  n_logfiles = %d\n", lc->n_logfiles);
    printf("  cur_logfiles_index = %d\n", lc->cur_logfiles_index);
    printf("  cur_fp = %p\n", lc->cur_fp);
    printf("  cur_lsn = %" PRIu64 "\n", lc->cur_lsn.lsn);
    printf("  last_direction = %d\n", (int) lc->last_direction);
}

static int lc_close_cur_logfile(TOKULOGCURSOR lc) {
    int r=0;
    if ( lc->is_open ) {
        r = fclose(lc->cur_fp);
        assert(0==r);
        lc->is_open = false;
    }
    return 0;
}

static toku_off_t lc_file_len(const char *name) {
   toku_struct_stat buf;
   int r = toku_stat(name, &buf); 
   assert(r == 0);
   return buf.st_size;
}

// Cat the file and throw away the contents.  This brings the file into the file system cache
// and makes subsequent accesses to it fast.  The intention is to speed up backward scans of the
// file.
static void lc_catfile(const char *fname, void *buffer, size_t buffer_size) {
    int fd = open(fname, O_RDONLY);
    if (fd >= 0) {
        while (1) {
            ssize_t r = read(fd, buffer, buffer_size);
            if ((int)r <= 0)
                break;
        }
        close(fd);
    }
}

static int lc_open_logfile(TOKULOGCURSOR lc, int index) {
    int r=0;
    assert( !lc->is_open );
    if( index == -1 || index >= lc->n_logfiles) return DB_NOTFOUND;
    lc_catfile(lc->logfiles[index], lc->buffer, lc->buffer_size);
    lc->cur_fp = fopen(lc->logfiles[index], "rb");
    if ( lc->cur_fp == NULL ) 
        return DB_NOTFOUND;
    r = setvbuf(lc->cur_fp, (char *) lc->buffer, _IOFBF, lc->buffer_size);
    assert(r == 0);
    // position fp past header, ignore 0 length file (t:2384)
    unsigned int version=0;
    if ( lc_file_len(lc->logfiles[index]) >= 12 ) {
        r = toku_read_logmagic(lc->cur_fp, &version);
        if (r!=0) 
            return DB_BADFORMAT;
        if (version < TOKU_LOG_MIN_SUPPORTED_VERSION || version > TOKU_LOG_VERSION)
            return DB_BADFORMAT;
    }
    // mark as open
    lc->is_open = true;
    return r;
}

static int lc_check_lsn(TOKULOGCURSOR lc, int dir) {
    int r=0;
    LSN lsn = toku_log_entry_get_lsn(&(lc->entry));
    if (((dir == LC_FORWARD)  && ( lsn.lsn != lc->cur_lsn.lsn + 1 )) ||
        ((dir == LC_BACKWARD) && ( lsn.lsn != lc->cur_lsn.lsn - 1 ))) {
//        int index = lc->cur_logfiles_index;
//        fprintf(stderr, "Bad LSN: %d %s direction = %d, lsn.lsn = %" PRIu64 ", cur_lsn.lsn=%" PRIu64 "\n", 
//                index, lc->logfiles[index], dir, lsn.lsn, lc->cur_lsn.lsn);
        if (tokuft_recovery_trace) 
            printf("DB_RUNRECOVERY: %s:%d r=%d\n", __FUNCTION__, __LINE__, 0);
        return LC_LSN_ERROR;
    }
    lc->cur_lsn.lsn = lsn.lsn;
    return r;
}

// toku_logcursor_create()
//   - returns a pointer to a logcursor

static int lc_create(TOKULOGCURSOR *lc, const char *log_dir) {

    // malloc a cursor
    TOKULOGCURSOR cursor = (TOKULOGCURSOR) toku_xmalloc(sizeof(struct toku_logcursor));
    // find logfiles in logdir
    cursor->is_open = false;
    cursor->cur_logfiles_index = 0;
    cursor->entry_valid = false;
    cursor->buffer_size = 1<<20;                       // use a 1MB stream buffer (setvbuf)
    cursor->buffer = toku_malloc(cursor->buffer_size); // it does not matter if it failes
    // cursor->logdir must be an absolute path
    if (toku_os_is_absolute_name(log_dir)) {
        cursor->logdir = (char *) toku_xmalloc(strlen(log_dir)+1);
        sprintf(cursor->logdir, "%s", log_dir);
    } else {
        char cwdbuf[PATH_MAX];
        char *cwd = getcwd(cwdbuf, PATH_MAX);
        assert(cwd);
        cursor->logdir = (char *) toku_xmalloc(strlen(cwd)+strlen(log_dir)+2);
        sprintf(cursor->logdir, "%s/%s", cwd, log_dir);
    }
    cursor->logfiles = NULL;
    cursor->n_logfiles = 0;
    cursor->cur_fp = NULL;
    cursor->cur_lsn.lsn=0;
    cursor->last_direction=LC_FIRST;
    
    *lc = cursor;
    return 0;
}

static int lc_fix_bad_logfile(TOKULOGCURSOR lc);

int toku_logcursor_create(TOKULOGCURSOR *lc, const char *log_dir) {
    TOKULOGCURSOR cursor;
    int r = lc_create(&cursor, log_dir);
    if ( r!=0 ) 
        return r;

    r = toku_logger_find_logfiles(cursor->logdir, &(cursor->logfiles), &(cursor->n_logfiles));
    if (r!=0) {
        toku_logcursor_destroy(&cursor);
    } else {
	*lc = cursor;
    }
    return r;
}

int toku_logcursor_create_for_file(TOKULOGCURSOR *lc, const char *log_dir, const char *log_file) {
    int r = lc_create(lc, log_dir);
    if ( r!=0 ) 
        return r;

    TOKULOGCURSOR cursor = *lc;
    int fullnamelen = strlen(cursor->logdir) + strlen(log_file) + 3;
    char *XMALLOC_N(fullnamelen, log_file_fullname);
    sprintf(log_file_fullname, "%s/%s", cursor->logdir, log_file);

    cursor->n_logfiles=1;

    char **XMALLOC(logfiles);
    cursor->logfiles = logfiles;
    cursor->logfiles[0] = log_file_fullname;
    *lc = cursor;
    return 0;
}

int toku_logcursor_destroy(TOKULOGCURSOR *lc) {
    int r=0;
    if ( *lc ) {
        if ( (*lc)->entry_valid ) {
            toku_log_free_log_entry_resources(&((*lc)->entry));
            (*lc)->entry_valid = false;
        }
        r = lc_close_cur_logfile(*lc);
        toku_logger_free_logfiles((*lc)->logfiles, (*lc)->n_logfiles);
        if ( (*lc)->logdir )   toku_free((*lc)->logdir);
        if ( (*lc)->buffer )   toku_free((*lc)->buffer);
        toku_free(*lc);
        *lc = NULL;
    }
    return r;
}

static int lc_log_read(TOKULOGCURSOR lc)
{
    int r = toku_log_fread(lc->cur_fp, &(lc->entry));
    while ( r == EOF ) { 
        // move to next file
        r = lc_close_cur_logfile(lc);                    
        if (r!=0) return r;
        if ( lc->cur_logfiles_index == lc->n_logfiles-1) return DB_NOTFOUND;
        lc->cur_logfiles_index++;
        r = lc_open_logfile(lc, lc->cur_logfiles_index); 
        if (r!=0) return r;
        r = toku_log_fread(lc->cur_fp, &(lc->entry));
    }
    if (r!=0) {
        toku_log_free_log_entry_resources(&(lc->entry));
        time_t tnow = time(NULL);
        if (r==DB_BADFORMAT) {
            fprintf(stderr, "%.24s PerconaFT bad log format in %s\n", ctime(&tnow), lc->logfiles[lc->cur_logfiles_index]);
        }
        else {
            fprintf(stderr, "%.24s PerconaFT unexpected log format error '%s' in %s\n", ctime(&tnow), strerror(r), lc->logfiles[lc->cur_logfiles_index]);
        }
    }
    return r;
}

static int lc_log_read_backward(TOKULOGCURSOR lc) 
{
    int r = toku_log_fread_backward(lc->cur_fp, &(lc->entry));
    while ( -1 == r) { // if within header length of top of file
        // move to previous file
        r = lc_close_cur_logfile(lc);
        if (r!=0) 
            return r;
        if ( lc->cur_logfiles_index == 0 ) 
            return DB_NOTFOUND;
        lc->cur_logfiles_index--;
        r = lc_open_logfile(lc, lc->cur_logfiles_index);
        if (r!=0) 
            return r;
        // seek to end
        r = fseek(lc->cur_fp, 0, SEEK_END);
        assert(0==r);
        r = toku_log_fread_backward(lc->cur_fp, &(lc->entry));
    }
    if (r!=0) {
        toku_log_free_log_entry_resources(&(lc->entry));
        time_t tnow = time(NULL);
        if (r==DB_BADFORMAT) {
            fprintf(stderr, "%.24s PerconaFT bad log format in %s\n", ctime(&tnow), lc->logfiles[lc->cur_logfiles_index]);
        }
        else {
            fprintf(stderr, "%.24s PerconaFT uUnexpected log format error '%s' in %s\n", ctime(&tnow), strerror(r), lc->logfiles[lc->cur_logfiles_index]);
        }
    }
    return r;
}

int toku_logcursor_next(TOKULOGCURSOR lc, struct log_entry **le) {
    int r=0;
    if ( lc->entry_valid ) {
        toku_log_free_log_entry_resources(&(lc->entry));
        lc->entry_valid = false;
        if (lc->last_direction == LC_BACKWARD) {
            struct log_entry junk;
            r = toku_log_fread(lc->cur_fp, &junk);
            assert(r == 0);
            toku_log_free_log_entry_resources(&junk);
        }
    } else {
        r = toku_logcursor_first(lc, le);
        return r;
    }
    // read the entry
    r = lc_log_read(lc);                   
    if (r!=0) return r;
    r = lc_check_lsn(lc, LC_FORWARD);  
    if (r!=0) return r;
    lc->last_direction = LC_FORWARD;
    lc->entry_valid = true;
    *le = &(lc->entry);
    return r;
}

int toku_logcursor_prev(TOKULOGCURSOR lc, struct log_entry **le) {
    int r=0;
    if ( lc->entry_valid ) {
        toku_log_free_log_entry_resources(&(lc->entry));
        lc->entry_valid = false;
        if (lc->last_direction == LC_FORWARD) {
            struct log_entry junk;
            r = toku_log_fread_backward(lc->cur_fp, &junk);
            assert(r == 0);
            toku_log_free_log_entry_resources(&junk);
        }
    } else {
        r = toku_logcursor_last(lc, le);
        return r;
    }
    // read the entry
    r = lc_log_read_backward(lc);
    if (r!=0) return r;
    r = lc_check_lsn(lc, LC_BACKWARD);
    if (r!=0) return r;
    lc->last_direction = LC_BACKWARD;
    lc->entry_valid = true;
    *le = &(lc->entry);
    return r;
}

int toku_logcursor_first(TOKULOGCURSOR lc, struct log_entry **le) {
    int r=0;
    if ( lc->entry_valid ) {
        toku_log_free_log_entry_resources(&(lc->entry));
        lc->entry_valid = false;
    }
    // close any but the first log file
    if ( lc->cur_logfiles_index != 0 ) {
        lc_close_cur_logfile(lc);
    }
    // open first log file if needed
    if ( !lc->is_open ) {
        r = lc_open_logfile(lc, 0);
        if (r!=0) 
            return r;
        lc->cur_logfiles_index = 0;
    }
    // read the entry
    r = lc_log_read(lc);
    if (r!=0) return r;

    r = lc_check_lsn(lc, LC_FIRST);
    if (r!=0) return r;
    lc->last_direction = LC_FIRST;
    lc->entry_valid = true;
    *le = &(lc->entry);
    return r;
}

//get last entry in the logfile specified by logcursor
int toku_logcursor_last(TOKULOGCURSOR lc, struct log_entry **le) {
    int r=0;
    if ( lc->entry_valid ) {
        toku_log_free_log_entry_resources(&(lc->entry));
        lc->entry_valid = false;
    }
    // close any but last log file
    if ( lc->cur_logfiles_index != lc->n_logfiles-1 ) {
        lc_close_cur_logfile(lc);
    }
    // open last log file if needed
    if ( !lc->is_open ) {
        r = lc_open_logfile(lc, lc->n_logfiles-1);
        if (r!=0)
            return r;
        lc->cur_logfiles_index = lc->n_logfiles-1;
    }
    while (1) {
        // seek to end
        r = fseek(lc->cur_fp, 0, SEEK_END);    assert(r==0);
        // read backward
        r = toku_log_fread_backward(lc->cur_fp, &(lc->entry));
        if (r==0) // got a good entry
            break;
        if (r>0) { 
            toku_log_free_log_entry_resources(&(lc->entry));
            // got an error, 
            // probably a corrupted last log entry due to a crash
            // try scanning forward from the beginning to find the last good entry
            time_t tnow = time(NULL);
            fprintf(stderr, "%.24s PerconaFT recovery repairing log\n", ctime(&tnow));
            r = lc_fix_bad_logfile(lc);
            if ( r != 0 ) {
                fprintf(stderr, "%.24s PerconaFT recovery repair unsuccessful\n", ctime(&tnow));
                return DB_BADFORMAT;
            }
            // try reading again
            r = toku_log_fread_backward(lc->cur_fp, &(lc->entry));
            if (r==0) // got a good entry
                break;
        }
        // move to previous file
        r = lc_close_cur_logfile(lc);
        if (r!=0) 
            return r;
        if ( lc->cur_logfiles_index == 0 ) 
            return DB_NOTFOUND;
        lc->cur_logfiles_index--;
        r = lc_open_logfile(lc, lc->cur_logfiles_index);
        if (r!=0) 
            return r;    
    }
    r = lc_check_lsn(lc, LC_LAST);
    if (r!=0)
        return r;
    lc->last_direction = LC_LAST;
    lc->entry_valid = true;
    *le = &(lc->entry);
    return r;
}

// return 0 if log exists, ENOENT if no log
int 
toku_logcursor_log_exists(const TOKULOGCURSOR lc) {
    int r;

    if (lc->n_logfiles) 
	r = 0;
    else
	r = ENOENT;

    return r;
}

// fix a logfile with a bad last entry
//  - return with fp pointing to end-of-file so that toku_logcursor_last can be retried
static int lc_fix_bad_logfile(TOKULOGCURSOR lc) {
    struct log_entry le;
    unsigned int version=0;
    int r = 0;

    r = fseek(lc->cur_fp, 0, SEEK_SET);                
    if ( r!=0 ) 
        return r;
    r = toku_read_logmagic(lc->cur_fp, &version);      
    if ( r!=0 ) 
        return r;
    if (version != TOKU_LOG_VERSION) 
        return -1;
    
    toku_off_t last_good_pos;
    last_good_pos = ftello(lc->cur_fp);
    while (1) {
        // initialize le 
        //  - reading incomplete entries can result in fields that cannot be freed
        memset(&le, 0, sizeof(le));
        r = toku_log_fread(lc->cur_fp, &le);
        toku_log_free_log_entry_resources(&le);
        if ( r!=0 ) 
            break;
        last_good_pos = ftello(lc->cur_fp);
    }
    // now have position of last good entry
    // 1) close the file
    // 2) truncate the file to remove the error
    // 3) reopen the file
    // 4) set the pos to last
    r = lc_close_cur_logfile(lc);                                   
    if ( r!=0 ) 
        return r;
    r = truncate(lc->logfiles[lc->n_logfiles - 1], last_good_pos);  
    if ( r!=0 ) 
        return r;
    r = lc_open_logfile(lc, lc->n_logfiles-1);                      
    if ( r!=0 ) 
        return r;
    r = fseek(lc->cur_fp, 0, SEEK_END);                             
    if ( r!=0 ) 
        return r;
    return 0;
}