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use Berkeley DB as on disk cache

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This commit is contained in:
Steffen Vogel 2016-10-26 19:14:29 -04:00
parent 7fadcacf6a
commit b0d1c1bfec
2 changed files with 68 additions and 67 deletions
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132
src/geonames.c
View file

@ -26,6 +26,12 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <sys/types.h>
#include <db.h>
#include <fcntl.h>
#include <limits.h>
#include <errno.h>
#include <curl/curl.h>
#include <json-c/json.h>
@ -72,9 +78,12 @@ static size_t json_parse_callback(void *contents, size_t size, size_t nmemb, voi
}
int geonames_lookup(const char *place, struct ln_lnlat_posn *result, char *name, int n) {
#ifdef GEONAMES_CACHE_SUPPORT
if (geonames_cache_lookup(place, result, name, n) == 0) {
int ret;
ret = geonames_cache_db(1, place, result);
if (ret == 0) {
strncpy(name, place, n);
#ifdef DEBUG
printf("debug: using cached geonames entry\n");
#endif
@ -124,7 +133,7 @@ int geonames_lookup(const char *place, struct ln_lnlat_posn *result, char *name,
int ret = geonames_parse(jobj, result, name, n);
if (!ret) {
#ifdef GEONAMES_CACHE_SUPPORT
geonames_cache_store(place, result, name, n);
geonames_cache_db(0, place, result);
#ifdef DEBUG
printf("debug: storing cache entry\n");
#endif
@ -152,74 +161,67 @@ int geonames_parse(struct json_object *jobj, struct ln_lnlat_posn *result, char
return 0;
}
int geonames_cache_lookup(const char *place, struct ln_lnlat_posn *result, char *name, int n) {
/* create filename */
int geonames_cache_db(int lookup, const char *place, struct ln_lnlat_posn *coords) {
int ret;
DB *dbp;
DBT key, data;
char filename[256];
char *place_lower;
place_lower = strdup(place);
if (!place_lower)
return -1;
for (char *p = place_lower; *p; ++p)
*p = tolower(*p);
snprintf(filename, sizeof(filename), "%s/%s", getenv("HOME"), GEONAMES_CACHE_FILE);
FILE *file = fopen(filename, "r"); /* should check the result */
if (file == NULL)
return -1;
char line[256];
while (fgets(line, sizeof(line), file)) {
/* replace newline at the end */
char *end = strchr(line, '\n');
if (end == NULL) {
return -1;
}
else
*end = '\0';
char *tok;
int col;
for (col = 0, tok = strtok(line, "\t"); tok != NULL; tok = strtok(NULL, "\t")) {
switch (col) {
case 0:
if (strcasecmp(tok, place) != 0) {
continue; /* skip row */
}
break;
case 1:
result->lat = strtod(tok, NULL);
break;
case 2:
result->lng = strtod(tok, NULL);
break;
case 3:
strncpy(name, tok, n);
fclose(file);
return 0; /* found! */
}
col++;
}
dbp = dbopen(filename, O_RDWR | O_CREAT, 0664, DB_BTREE, NULL);
if (!dbp) {
fprintf(stderr, "dbopen: %s\n", strerror(errno));
exit (1);
}
memset(&key, 0, sizeof(key));
memset(&data, 0, sizeof(data));
fclose(file);
return 1; /* not found */
}
key.data = place_lower;
key.size = strlen(place_lower) + 1;
if (lookup) {
ret = dbp->get(dbp, &key, &data, 0);
if (ret)
goto err;
int geonames_cache_store(const char *place, struct ln_lnlat_posn *result, char *name, int n) {
/* create filename */
char filename[256];
snprintf(filename, sizeof(filename), "%s/%s", getenv("HOME"), GEONAMES_CACHE_FILE);
FILE* file = fopen(filename, "a+"); /* should check the result */
if (file == NULL)
return -1;
/* build cache entry */
char line[256];
snprintf(line, sizeof(line), "%s\t%.5f\t%.5f\t%s\n", place, result->lat, result->lng, name);
if (fputs(line, file) == EOF) {
fclose(file);
return -1;
#ifdef DEBUG
printf("debug: cache key retrieved: %s => %f %f.\n", (char *) key.data,
((struct ln_lnlat_posn *) data.data)->lat,
((struct ln_lnlat_posn *) data.data)->lng);
#endif
if (data.size != sizeof(struct ln_lnlat_posn))
goto err;
memcpy(coords, data.data, sizeof(struct ln_lnlat_posn));
}
else {
data.data = coords;
data.size = sizeof(struct ln_lnlat_posn);
ret = dbp->put(dbp, &key, &data, 0);
if (ret)
goto err;
fclose(file);
return 0;
#ifdef DEBUG
printf("debug: cache key stored: %s => %f %f.\n", (char *) key.data,
((struct ln_lnlat_posn *) data.data)->lat,
((struct ln_lnlat_posn *) data.data)->lng);
#endif
}
err:
dbp->close(dbp);
return ret;
}

3
src/geonames.h
View file

@ -35,8 +35,7 @@ struct ln_lnlat_posn;
#define GEONAMES_CACHE_FILE ".geonames.cache" /* in users home dir */
int geonames_lookup(const char *place, struct ln_lnlat_posn *coords, char *name, int n);
int geonames_cache_lookup(const char *place, struct ln_lnlat_posn *result, char *name, int n);
int geonames_cache_store(const char *place, struct ln_lnlat_posn *result, char *name, int n);
int geonames_cache_db(int lookup, const char *place, struct ln_lnlat_posn *coords);
int geonames_parse(struct json_object *jobj, struct ln_lnlat_posn *result, char *name, int n);
#endif /* _GEONAMES_H_ */