diff options
Diffstat (limited to 'src/shuf.c')
| -rw-r--r-- | src/shuf.c | 365 |
1 files changed, 305 insertions, 60 deletions
@@ -1,6 +1,6 @@ /* Shuffle lines of text. - Copyright (C) 2006-2013 Free Software Foundation, Inc. + Copyright (C) 2006-2014 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -25,6 +25,7 @@ #include "error.h" #include "fadvise.h" #include "getopt.h" +#include "linebuffer.h" #include "quote.h" #include "quotearg.h" #include "randint.h" @@ -38,6 +39,18 @@ #define AUTHORS proper_name ("Paul Eggert") +/* For reservoir-sampling, allocate the reservoir lines in batches. */ +enum { RESERVOIR_LINES_INCREMENT = 1024 }; + +/* reservoir-sampling introduces CPU overhead for small inputs. + So only enable it for inputs >= this limit. + This limit was determined using these commands: + $ for p in $(seq 7); do src/seq $((10**$p)) > 10p$p.in; done + $ for p in $(seq 7); do time shuf-nores -n10 10p$p.in >/dev/null; done + $ for p in $(seq 7); do time shuf -n10 10p$p.in >/dev/null; done .*/ +enum { RESERVOIR_MIN_INPUT = 8192 * 1024 }; + + void usage (int status) { @@ -63,7 +76,10 @@ Write a random permutation of the input lines to standard output.\n\ -n, --head-count=COUNT output at most COUNT lines\n\ -o, --output=FILE write result to FILE instead of standard output\n\ --random-source=FILE get random bytes from FILE\n\ - -z, --zero-terminated end lines with 0 byte, not newline\n\ + -r, --repeat output lines can be repeated\n\ +"), stdout); + fputs (_("\ + -z, --zero-terminated line delimiter is NUL, not newline\n\ "), stdout); fputs (HELP_OPTION_DESCRIPTION, stdout); fputs (VERSION_OPTION_DESCRIPTION, stdout); @@ -91,18 +107,13 @@ static struct option const long_opts[] = {"head-count", required_argument, NULL, 'n'}, {"output", required_argument, NULL, 'o'}, {"random-source", required_argument, NULL, RANDOM_SOURCE_OPTION}, + {"repeat", no_argument, NULL, 'r'}, {"zero-terminated", no_argument, NULL, 'z'}, {GETOPT_HELP_OPTION_DECL}, {GETOPT_VERSION_OPTION_DECL}, {0, 0, 0, 0}, }; -static bool -input_numbers_option_used (size_t lo_input, size_t hi_input) -{ - return ! (lo_input == SIZE_MAX && hi_input == 0); -} - static void input_from_argv (char **operand, int n_operands, char eolbyte) { @@ -135,6 +146,114 @@ next_line (char *line, char eolbyte, size_t n) return p + 1; } +/* Return the size of the input if possible or OFF_T_MAX if not. */ + +static off_t +input_size (void) +{ + off_t file_size; + + struct stat stat_buf; + if (fstat (STDIN_FILENO, &stat_buf) != 0) + return OFF_T_MAX; + if (usable_st_size (&stat_buf)) + file_size = stat_buf.st_size; + else + return OFF_T_MAX; + + off_t input_offset = lseek (STDIN_FILENO, 0, SEEK_CUR); + if (input_offset < 0) + return OFF_T_MAX; + + file_size -= input_offset; + + return file_size; +} + +/* Read all lines and store up to K permuted lines in *OUT_RSRV. + Return the number of lines read, up to a maximum of K. */ + +static size_t +read_input_reservoir_sampling (FILE *in, char eolbyte, size_t k, + struct randint_source *s, + struct linebuffer **out_rsrv) +{ + randint n_lines = 0; + size_t n_alloc_lines = MIN (k, RESERVOIR_LINES_INCREMENT); + struct linebuffer *line = NULL; + struct linebuffer *rsrv; + + rsrv = xcalloc (n_alloc_lines, sizeof (struct linebuffer)); + + /* Fill the first K lines, directly into the reservoir. */ + while (n_lines < k + && (line = + readlinebuffer_delim (&rsrv[n_lines], in, eolbyte)) != NULL) + { + n_lines++; + + /* Enlarge reservoir. */ + if (n_lines >= n_alloc_lines) + { + n_alloc_lines += RESERVOIR_LINES_INCREMENT; + rsrv = xnrealloc (rsrv, n_alloc_lines, sizeof (struct linebuffer)); + memset (&rsrv[n_lines], 0, + RESERVOIR_LINES_INCREMENT * sizeof (struct linebuffer)); + } + } + + /* last line wasn't NULL - so there may be more lines to read. */ + if (line != NULL) + { + struct linebuffer dummy; + initbuffer (&dummy); /* space for lines not put in reservoir. */ + + /* Choose the fate of the next line, with decreasing probability (as + n_lines increases in size). + + If the line will be used, store it directly in the reservoir. + Otherwise, store it in dummy space. + + With 'struct linebuffer', storing into existing buffer will reduce + re-allocations (will only re-allocate if the new line is longer than + the currently allocated space). */ + do + { + randint j = randint_choose (s, n_lines + 1); /* 0 .. n_lines. */ + line = (j < k) ? (&rsrv[j]) : (&dummy); + } + while (readlinebuffer_delim (line, in, eolbyte) != NULL && n_lines++); + + if (! n_lines) + error (EXIT_FAILURE, EOVERFLOW, _("too many input lines")); + + freebuffer (&dummy); + } + + /* no more input lines, or an input error. */ + if (ferror (in)) + error (EXIT_FAILURE, errno, _("read error")); + + *out_rsrv = rsrv; + return MIN (k, n_lines); +} + +static int +write_permuted_output_reservoir (size_t n_lines, struct linebuffer *lines, + size_t const *permutation) +{ + size_t i; + + for (i = 0; i < n_lines; i++) + { + const struct linebuffer *p = &lines[permutation[i]]; + if (fwrite (p->buffer, sizeof (char), p->length, stdout) != p->length) + return -1; + } + + return 0; +} + /* Read data from file IN. Input lines are delimited by EOLBYTE; silently append a trailing EOLBYTE if the file ends in some other byte. Store a pointer to the resulting array of lines into *PLINE. @@ -152,6 +271,15 @@ read_input (FILE *in, char eolbyte, char ***pline) size_t i; size_t n_lines; + /* TODO: We should limit the amount of data read here, + to less than RESERVOIR_MIN_INPUT. I.E. adjust fread_file() to support + taking a byte limit. We'd then need to ensure we handle a line spanning + this boundary. With that in place we could set use_reservoir_sampling + when used==RESERVOIR_MIN_INPUT, and have read_input_reservoir_sampling() + call a wrapper function to populate a linebuffer from the internal pline + or if none left, stdin. Doing that would give better performance by + avoiding the reservoir CPU overhead when reading < RESERVOIR_MIN_INPUT + from a pipe, and allow us to dispense with the input_size() function. */ if (!(buf = fread_file (in, &used))) error (EXIT_FAILURE, errno, _("read error")); @@ -173,27 +301,81 @@ read_input (FILE *in, char eolbyte, char ***pline) return n_lines; } +/* Output N_LINES lines to stdout from LINE array, + chosen by the indices in PERMUTATION. + PERMUTATION and LINE must have at least N_LINES elements. + Strings in LINE must include the line-terminator character. */ static int -write_permuted_output (size_t n_lines, char * const *line, size_t lo_input, - size_t const *permutation, char eolbyte) +write_permuted_lines (size_t n_lines, char *const *line, + size_t const *permutation) { size_t i; - if (line) - for (i = 0; i < n_lines; i++) - { - char * const *p = line + permutation[i]; - size_t len = p[1] - p[0]; - if (fwrite (p[0], sizeof *p[0], len, stdout) != len) - return -1; - } - else - for (i = 0; i < n_lines; i++) - { - unsigned long int n = lo_input + permutation[i]; - if (printf ("%lu%c", n, eolbyte) < 0) - return -1; - } + for (i = 0; i < n_lines; i++) + { + char *const *p = line + permutation[i]; + size_t len = p[1] - p[0]; + if (fwrite (p[0], sizeof *p[0], len, stdout) != len) + return -1; + } + + return 0; +} + +/* Output N_LINES of numbers to stdout, from PERMUTATION array. + PERMUTATION must have at least N_LINES elements. */ +static int +write_permuted_numbers (size_t n_lines, size_t lo_input, + size_t const *permutation, char eolbyte) +{ + size_t i; + + for (i = 0; i < n_lines; i++) + { + unsigned long int n = lo_input + permutation[i]; + if (printf ("%lu%c", n, eolbyte) < 0) + return -1; + } + + return 0; +} + +/* Output COUNT numbers to stdout, chosen randomly from range + LO_INPUT through HI_INPUT. */ +static int +write_random_numbers (struct randint_source *s, size_t count, + size_t lo_input, size_t hi_input, char eolbyte) +{ + size_t i; + const randint range = hi_input - lo_input + 1; + + for (i = 0; i < count; i++) + { + unsigned long int j = lo_input + randint_choose (s, range); + if (printf ("%lu%c", j, eolbyte) < 0) + return -1; + } + + return 0; +} + +/* Output COUNT lines to stdout from LINES array. + LINES must have at least N_LINES elements in it. + Strings in LINES_ must include the line-terminator character. */ +static int +write_random_lines (struct randint_source *s, size_t count, + char *const *lines, size_t n_lines) +{ + size_t i; + + for (i = 0; i < count; i++) + { + const randint j = randint_choose (s, n_lines); + char *const *p = lines + j; + size_t len = p[1] - p[0]; + if (fwrite (p[0], sizeof *p[0], len, stdout) != len) + return -1; + } return 0; } @@ -202,6 +384,7 @@ int main (int argc, char **argv) { bool echo = false; + bool input_range = false; size_t lo_input = SIZE_MAX; size_t hi_input = 0; size_t head_lines = SIZE_MAX; @@ -209,14 +392,18 @@ main (int argc, char **argv) char *random_source = NULL; char eolbyte = '\n'; char **input_lines = NULL; + bool use_reservoir_sampling = false; + bool repeat = false; int optc; int n_operands; char **operand; size_t n_lines; - char **line; + char **line = NULL; + struct linebuffer *reservoir = NULL; struct randint_source *randint_source; - size_t *permutation; + size_t *permutation = NULL; + int i; initialize_main (&argc, &argv); set_program_name (argv[0]); @@ -226,7 +413,7 @@ main (int argc, char **argv) atexit (close_stdout); - while ((optc = getopt_long (argc, argv, "ei:n:o:z", long_opts, NULL)) != -1) + while ((optc = getopt_long (argc, argv, "ei:n:o:rz", long_opts, NULL)) != -1) switch (optc) { case 'e': @@ -240,8 +427,9 @@ main (int argc, char **argv) char const *hi_optarg = optarg; bool invalid = !p; - if (input_numbers_option_used (lo_input, hi_input)) + if (input_range) error (EXIT_FAILURE, 0, _("multiple -i options specified")); + input_range = true; if (p) { @@ -291,6 +479,10 @@ main (int argc, char **argv) random_source = optarg; break; + case 'r': + repeat = true; + break; + case 'z': eolbyte = '\0'; break; @@ -304,67 +496,113 @@ main (int argc, char **argv) n_operands = argc - optind; operand = argv + optind; + /* Check invalid usage. */ + if (echo && input_range) + { + error (0, 0, _("cannot combine -e and -i options")); + usage (EXIT_FAILURE); + } + if (input_range ? 0 < n_operands : !echo && 1 < n_operands) + { + error (0, 0, _("extra operand %s"), quote (operand[1])); + usage (EXIT_FAILURE); + } + + /* Prepare input. */ if (echo) { - if (input_numbers_option_used (lo_input, hi_input)) - error (EXIT_FAILURE, 0, _("cannot combine -e and -i options")); input_from_argv (operand, n_operands, eolbyte); n_lines = n_operands; line = operand; } - else if (input_numbers_option_used (lo_input, hi_input)) + else if (input_range) { - if (n_operands) - { - error (0, 0, _("extra operand %s"), quote (operand[0])); - usage (EXIT_FAILURE); - } n_lines = hi_input - lo_input + 1; line = NULL; } else { - switch (n_operands) - { - case 0: - break; - - case 1: - if (! (STREQ (operand[0], "-") || freopen (operand[0], "r", stdin))) - error (EXIT_FAILURE, errno, "%s", operand[0]); - break; - - default: - error (0, 0, _("extra operand %s"), quote (operand[1])); - usage (EXIT_FAILURE); - } + /* If an input file is specified, re-open it as stdin. */ + if (n_operands == 1) + if (! (STREQ (operand[0], "-") || ! head_lines + || freopen (operand[0], "r", stdin))) + error (EXIT_FAILURE, errno, "%s", operand[0]); fadvise (stdin, FADVISE_SEQUENTIAL); - n_lines = read_input (stdin, eolbyte, &input_lines); - line = input_lines; + if (! repeat && head_lines != SIZE_MAX + && (! head_lines || input_size () > RESERVOIR_MIN_INPUT)) + { + use_reservoir_sampling = true; + n_lines = SIZE_MAX; /* unknown number of input lines, for now. */ + } + else + { + n_lines = read_input (stdin, eolbyte, &input_lines); + line = input_lines; + } } - head_lines = MIN (head_lines, n_lines); + if (! repeat) + head_lines = MIN (head_lines, n_lines); randint_source = randint_all_new (random_source, - randperm_bound (head_lines, n_lines)); + (use_reservoir_sampling || repeat + ? SIZE_MAX + : randperm_bound (head_lines, n_lines))); if (! randint_source) error (EXIT_FAILURE, errno, "%s", quotearg_colon (random_source)); + if (use_reservoir_sampling) + { + /* Instead of reading the entire file into 'line', + use reservoir-sampling to store just "head_lines" random lines. */ + n_lines = read_input_reservoir_sampling (stdin, eolbyte, head_lines, + randint_source, &reservoir); + head_lines = n_lines; + } + /* Close stdin now, rather than earlier, so that randint_all_new doesn't have to worry about opening something other than stdin. */ - if (! (echo || input_numbers_option_used (lo_input, hi_input)) + if (! (echo || input_range) && (fclose (stdin) != 0)) error (EXIT_FAILURE, errno, _("read error")); - permutation = randperm_new (randint_source, head_lines, n_lines); + if (!repeat) + permutation = randperm_new (randint_source, head_lines, n_lines); if (outfile && ! freopen (outfile, "w", stdout)) error (EXIT_FAILURE, errno, "%s", quotearg_colon (outfile)); - if (write_permuted_output (head_lines, line, lo_input, permutation, eolbyte) - != 0) + + /* Generate output according to requested method */ + if (repeat) + { + if (head_lines == 0) + i = 0; + else + { + if (n_lines == 0) + error (EXIT_FAILURE, 0, _("no lines to repeat")); + if (input_range) + i = write_random_numbers (randint_source, head_lines, + lo_input, hi_input, eolbyte); + else + i = write_random_lines (randint_source, head_lines, line, n_lines); + } + } + else + { + if (use_reservoir_sampling) + i = write_permuted_output_reservoir (n_lines, reservoir, permutation); + else if (input_range) + i = write_permuted_numbers (head_lines, lo_input, + permutation, eolbyte); + else + i = write_permuted_lines (head_lines, line, permutation); + } + + if (i != 0) error (EXIT_FAILURE, errno, _("write error")); #ifdef lint @@ -375,7 +613,14 @@ main (int argc, char **argv) free (input_lines[0]); free (input_lines); } + if (reservoir) + { + size_t j; + for (j = 0; j < n_lines; ++j) + freebuffer (&reservoir[j]); + free (reservoir); + } #endif - return EXIT_SUCCESS; + exit (EXIT_SUCCESS); } |