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When looking up macro values while the macro tables are being built
in makewhatis(8), use ohash rather than linear searches.

This was identified as the main makewhatis(8) performance bottleneck
by Baptiste Daroussin <bapt at FreeBSD>, who also suggested part
of the improved algorithm.

This reduces the run time of "makewhatis /usr/share/man" from eleven
to five seconds on my notebook.  Note that the changed code is not
used in apropos(1), so don't expect speedups there.

While here, sort macro values asciibetically, to improve reproducibility -
which still isn't perfect, but getting better.

/*	$Id: dba.c,v 1.9 2017/01/15 15:28:55 schwarze Exp $ */
/*
 * Copyright (c) 2016, 2017 Ingo Schwarze <schwarze@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Allocation-based version of the mandoc database, for read-write access.
 * The interface is defined in "dba.h".
 */
#include "config.h"

#include <sys/types.h>
#if HAVE_ENDIAN
#include <endian.h>
#elif HAVE_SYS_ENDIAN
#include <sys/endian.h>
#elif HAVE_NTOHL
#include <arpa/inet.h>
#endif
#include <errno.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "mandoc_aux.h"
#include "mandoc_ohash.h"
#include "mansearch.h"
#include "dba_write.h"
#include "dba_array.h"
#include "dba.h"

struct macro_entry {
	struct dba_array	*pages;
	char			 value[];
};

static void	*prepend(const char *, char);
static void	 dba_pages_write(struct dba_array *);
static int	 compare_names(const void *, const void *);
static int	 compare_strings(const void *, const void *);

static struct macro_entry
		*get_macro_entry(struct ohash *, const char *, int32_t);
static void	 dba_macros_write(struct dba_array *);
static void	 dba_macro_write(struct ohash *);
static int	 compare_entries(const void *, const void *);


/*** top-level functions **********************************************/

struct dba *
dba_new(int32_t npages)
{
	struct dba	*dba;
	struct ohash	*macro;
	int32_t		 im;

	dba = mandoc_malloc(sizeof(*dba));
	dba->pages = dba_array_new(npages, DBA_GROW);
	dba->macros = dba_array_new(MACRO_MAX, 0);
	for (im = 0; im < MACRO_MAX; im++) {
		macro = mandoc_malloc(sizeof(*macro));
		mandoc_ohash_init(macro, 4,
		    offsetof(struct macro_entry, value));
		dba_array_set(dba->macros, im, macro);
	}
	return dba;
}

void
dba_free(struct dba *dba)
{
	struct dba_array	*page;
	struct ohash		*macro;
	struct macro_entry	*entry;
	unsigned int		 slot;

	dba_array_FOREACH(dba->macros, macro) {
		for (entry = ohash_first(macro, &slot); entry != NULL;
		     entry = ohash_next(macro, &slot)) {
			dba_array_free(entry->pages);
			free(entry);
		}
		ohash_delete(macro);
		free(macro);
	}
	dba_array_free(dba->macros);

	dba_array_undel(dba->pages);
	dba_array_FOREACH(dba->pages, page) {
		dba_array_free(dba_array_get(page, DBP_NAME));
		dba_array_free(dba_array_get(page, DBP_SECT));
		dba_array_free(dba_array_get(page, DBP_ARCH));
		free(dba_array_get(page, DBP_DESC));
		dba_array_free(dba_array_get(page, DBP_FILE));
		dba_array_free(page);
	}
	dba_array_free(dba->pages);

	free(dba);
}

/*
 * Write the complete mandoc database to disk; the format is:
 * - One integer each for magic and version.
 * - One pointer each to the macros table and to the final magic.
 * - The pages table.
 * - The macros table.
 * - And at the very end, the magic integer again.
 */
int
dba_write(const char *fname, struct dba *dba)
{
	int	 save_errno;
	int32_t	 pos_end, pos_macros, pos_macros_ptr;

	if (dba_open(fname) == -1)
		return -1;
	dba_int_write(MANDOCDB_MAGIC);
	dba_int_write(MANDOCDB_VERSION);
	pos_macros_ptr = dba_skip(1, 2);
	dba_pages_write(dba->pages);
	pos_macros = dba_tell();
	dba_macros_write(dba->macros);
	pos_end = dba_tell();
	dba_int_write(MANDOCDB_MAGIC);
	dba_seek(pos_macros_ptr);
	dba_int_write(pos_macros);
	dba_int_write(pos_end);
	if (dba_close() == -1) {
		save_errno = errno;
		unlink(fname);
		errno = save_errno;
		return -1;
	}
	return 0;
}


/*** functions for handling pages *************************************/

/*
 * Create a new page and append it to the pages table.
 */
struct dba_array *
dba_page_new(struct dba_array *pages, const char *arch,
    const char *desc, const char *file, enum form form)
{
	struct dba_array *page, *entry;

	page = dba_array_new(DBP_MAX, 0);
	entry = dba_array_new(1, DBA_STR | DBA_GROW);
	dba_array_add(page, entry);
	entry = dba_array_new(1, DBA_STR | DBA_GROW);
	dba_array_add(page, entry);
	if (arch != NULL && *arch != '\0') {
		entry = dba_array_new(1, DBA_STR | DBA_GROW);
		dba_array_add(entry, (void *)arch);
	} else
		entry = NULL;
	dba_array_add(page, entry);
	dba_array_add(page, mandoc_strdup(desc));
	entry = dba_array_new(1, DBA_STR | DBA_GROW);
	dba_array_add(entry, prepend(file, form));
	dba_array_add(page, entry);
	dba_array_add(pages, page);
	return page;
}

/*
 * Add a section, architecture, or file name to an existing page.
 * Passing the NULL pointer for the architecture makes the page MI.
 * In that case, any earlier or later architectures are ignored.
 */
void
dba_page_add(struct dba_array *page, int32_t ie, const char *str)
{
	struct dba_array	*entries;
	char			*entry;

	entries = dba_array_get(page, ie);
	if (ie == DBP_ARCH) {
		if (entries == NULL)
			return;
		if (str == NULL || *str == '\0') {
			dba_array_free(entries);
			dba_array_set(page, DBP_ARCH, NULL);
			return;
		}
	}
	if (*str == '\0')
		return;
	dba_array_FOREACH(entries, entry) {
		if (ie == DBP_FILE && *entry < ' ')
			entry++;
		if (strcmp(entry, str) == 0)
			return;
	}
	dba_array_add(entries, (void *)str);
}

/*
 * Add an additional name to an existing page.
 */
void
dba_page_alias(struct dba_array *page, const char *name, uint64_t mask)
{
	struct dba_array	*entries;
	char			*entry;
	char			 maskbyte;

	if (*name == '\0')
		return;
	maskbyte = mask & NAME_MASK;
	entries = dba_array_get(page, DBP_NAME);
	dba_array_FOREACH(entries, entry) {
		if (strcmp(entry + 1, name) == 0) {
			*entry |= maskbyte;
			return;
		}
	}
	dba_array_add(entries, prepend(name, maskbyte));
}

/*
 * Return a pointer to a temporary copy of instr with inbyte prepended.
 */
static void *
prepend(const char *instr, char inbyte)
{
	static char	*outstr = NULL;
	static size_t	 outlen = 0;
	size_t		 newlen;

	newlen = strlen(instr) + 1;
	if (newlen > outlen) {
		outstr = mandoc_realloc(outstr, newlen + 1);
		outlen = newlen;
	}
	*outstr = inbyte;
	memcpy(outstr + 1, instr, newlen);
	return outstr;
}

/*
 * Write the pages table to disk; the format is:
 * - One integer containing the number of pages.
 * - For each page, five pointers to the names, sections,
 *   architectures, description, and file names of the page.
 *   MI pages write 0 instead of the architecture pointer.
 * - One list each for names, sections, architectures, descriptions and
 *   file names.  The description for each page ends with a NUL byte.
 *   For all the other lists, each string ends with a NUL byte,
 *   and the last string for a page ends with two NUL bytes.
 * - To assure alignment of following integers,
 *   the end is padded with NUL bytes up to a multiple of four bytes.
 */
static void
dba_pages_write(struct dba_array *pages)
{
	struct dba_array	*page, *entry;
	int32_t			 pos_pages, pos_end;

	pos_pages = dba_array_writelen(pages, 5);
	dba_array_FOREACH(pages, page) {
		dba_array_setpos(page, DBP_NAME, dba_tell());
		entry = dba_array_get(page, DBP_NAME);
		dba_array_sort(entry, compare_names);
		dba_array_writelst(entry);
	}
	dba_array_FOREACH(pages, page) {
		dba_array_setpos(page, DBP_SECT, dba_tell());
		entry = dba_array_get(page, DBP_SECT);
		dba_array_sort(entry, compare_strings);
		dba_array_writelst(entry);
	}
	dba_array_FOREACH(pages, page) {
		if ((entry = dba_array_get(page, DBP_ARCH)) != NULL) {
			dba_array_setpos(page, DBP_ARCH, dba_tell());
			dba_array_sort(entry, compare_strings);
			dba_array_writelst(entry);
		} else
			dba_array_setpos(page, DBP_ARCH, 0);
	}
	dba_array_FOREACH(pages, page) {
		dba_array_setpos(page, DBP_DESC, dba_tell());
		dba_str_write(dba_array_get(page, DBP_DESC));
	}
	dba_array_FOREACH(pages, page) {
		dba_array_setpos(page, DBP_FILE, dba_tell());
		dba_array_writelst(dba_array_get(page, DBP_FILE));
	}
	pos_end = dba_align();
	dba_seek(pos_pages);
	dba_array_FOREACH(pages, page)
		dba_array_writepos(page);
	dba_seek(pos_end);
}

static int
compare_names(const void *vp1, const void *vp2)
{
	const char	*cp1, *cp2;
	int		 diff;

	cp1 = *(char **)vp1;
	cp2 = *(char **)vp2;
	return (diff = *cp2 - *cp1) ? diff :
	    strcasecmp(cp1 + 1, cp2 + 1);
}

static int
compare_strings(const void *vp1, const void *vp2)
{
	const char	*cp1, *cp2;

	cp1 = *(char **)vp1;
	cp2 = *(char **)vp2;
	return strcmp(cp1, cp2);
}

/*** functions for handling macros ************************************/

/*
 * In the hash table for a single macro, look up an entry by
 * the macro value or add an empty one if it doesn't exist yet.
 */
static struct macro_entry *
get_macro_entry(struct ohash *macro, const char *value, int32_t np)
{
	struct macro_entry	*entry;
	size_t			 len;
	unsigned int		 slot;

	slot = ohash_qlookup(macro, value);
	if ((entry = ohash_find(macro, slot)) == NULL) {
		len = strlen(value) + 1;
		entry = mandoc_malloc(sizeof(*entry) + len);
		memcpy(&entry->value, value, len);
		entry->pages = dba_array_new(np, DBA_GROW);
		ohash_insert(macro, slot, entry);
	}
	return entry;
}

/*
 * In addition to get_macro_entry(), add multiple page references,
 * converting them from the on-disk format (byte offsets in the file)
 * to page pointers in memory.
 */
void
dba_macro_new(struct dba *dba, int32_t im, const char *value,
    const int32_t *pp)
{
	struct macro_entry	*entry;
	const int32_t		*ip;
	int32_t			 np;

	np = 0;
	for (ip = pp; *ip; ip++)
		np++;

	entry = get_macro_entry(dba_array_get(dba->macros, im), value, np);
	for (ip = pp; *ip; ip++)
		dba_array_add(entry->pages, dba_array_get(dba->pages,
		    be32toh(*ip) / 5 / sizeof(*ip) - 1));
}

/*
 * In addition to get_macro_entry(), add one page reference,
 * directly taking the in-memory page pointer as an argument.
 */
void
dba_macro_add(struct dba_array *macros, int32_t im, const char *value,
    struct dba_array *page)
{
	struct macro_entry	*entry;

	if (*value == '\0')
		return;
	entry = get_macro_entry(dba_array_get(macros, im), value, 1);
	dba_array_add(entry->pages, page);
}

/*
 * Write the macros table to disk; the format is:
 * - The number of macro tables (actually, MACRO_MAX).
 * - That number of pointers to the individual macro tables.
 * - The individual macro tables.
 */
static void
dba_macros_write(struct dba_array *macros)
{
	struct ohash		*macro;
	int32_t			 im, pos_macros, pos_end;

	pos_macros = dba_array_writelen(macros, 1);
	im = 0;
	dba_array_FOREACH(macros, macro) {
		dba_array_setpos(macros, im++, dba_tell());
		dba_macro_write(macro);
	}
	pos_end = dba_tell();
	dba_seek(pos_macros);
	dba_array_writepos(macros);
	dba_seek(pos_end);
}

/*
 * Write one individual macro table to disk; the format is:
 * - The number of entries in the table.
 * - For each entry, two pointers, the first one to the value
 *   and the second one to the list of pages.
 * - A list of values, each ending in a NUL byte.
 * - To assure alignment of following integers,
 *   padding with NUL bytes up to a multiple of four bytes.
 * - A list of pointers to pages, each list ending in a 0 integer.
 */
static void
dba_macro_write(struct ohash *macro)
{
	struct macro_entry	**entries, *entry;
	struct dba_array	 *page;
	int32_t			 *kpos, *dpos;
	unsigned int		  ie, ne, slot;
	int			  use;
	int32_t			  addr, pos_macro, pos_end;

	/* Temporary storage for filtering and sorting. */

	ne = ohash_entries(macro);
	entries = mandoc_reallocarray(NULL, ne, sizeof(*entries));
	kpos = mandoc_reallocarray(NULL, ne, sizeof(*kpos));
	dpos = mandoc_reallocarray(NULL, ne, sizeof(*dpos));

	/* Build a list of non-empty entries and sort it. */

	ne = 0;
	for (entry = ohash_first(macro, &slot); entry != NULL;
	     entry = ohash_next(macro, &slot)) {
		use = 0;
		dba_array_FOREACH(entry->pages, page)
			if (dba_array_getpos(page))
				use = 1;
		if (use)
			entries[ne++] = entry;
	}
	qsort(entries, ne, sizeof(*entries), compare_entries);

	/* Number of entries, and space for the pointer pairs. */

	dba_int_write(ne);
	pos_macro = dba_skip(2, ne);

	/* String table. */

	for (ie = 0; ie < ne; ie++) {
		kpos[ie] = dba_tell();
		dba_str_write(entries[ie]->value);
	}
	dba_align();

	/* Pages table. */

	for (ie = 0; ie < ne; ie++) {
		dpos[ie] = dba_tell();
		dba_array_FOREACH(entries[ie]->pages, page)
			if ((addr = dba_array_getpos(page)))
				dba_int_write(addr);
		dba_int_write(0);
	}
	pos_end = dba_tell();

	/* Fill in the pointer pairs. */

	dba_seek(pos_macro);
	for (ie = 0; ie < ne; ie++) {
		dba_int_write(kpos[ie]);
		dba_int_write(dpos[ie]);
	}
	dba_seek(pos_end);

	free(entries);
	free(kpos);
	free(dpos);
}

static int
compare_entries(const void *vp1, const void *vp2)
{
	const struct macro_entry *ep1, *ep2;

	ep1 = *(struct macro_entry **)vp1;
	ep2 = *(struct macro_entry **)vp2;
	return strcmp(ep1->value, ep2->value);
}