Refactor to check files asynchrously using POSIX timers.

src/Makefile.am

 AUTOMAKE_OPTIONS = subdir-objects
 
 AM_CFLAGS = $(VARNISHAPI_CFLAGS) -Wall -Werror -Wextra -std=c99
-AM_LDFLAGS = $(VARNISHAPI_LIBS) -ldl
+AM_LDFLAGS = $(VARNISHAPI_LIBS) -ldl -lrt
 
 vmod_LTLIBRARIES = libvmod_file.la
 

src/tests/get.vtc

@@ -2,7 +2,7 @@
 
 varnishtest "reader constructor and .get()"
 
-shell {echo "foo bar baz quux" > ${tmpdir}/file}
+shell {echo -n "foo bar baz quux" > ${tmpdir}/file}
 
 varnish v1 -vcl+backend {
 	import ${vmod_file};

src/vmod_file.c

@@ -26,7 +26,7 @@
  * SUCH DAMAGE.
  */
 
-/* for strdup() */
+/* for strdup() and timer_* */
 #define _POSIX_C_SOURCE 200809L
 
 #include "config.h"
@@ -38,103 +38,149 @@
 #include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
+#include <signal.h>
+#include <stdio.h>
 
 #include "cache/cache.h"
 #include "vcl.h"
+#include "vtim.h"
 
 #include "vcc_if.h"
 
-#define VFAIL(ctx, fmt, ...) \
+#define FAIL(ctx, msg)					\
+        VRT_fail((ctx), "vmod file failure: " msg)
+
+#define VFAIL(ctx, fmt, ...)					\
         VRT_fail((ctx), "vmod file failure: " fmt, __VA_ARGS__)
 
+#define VERRMSG(rdr, fmt, ...)						\
+	snprintf((rdr)->errbuf, (rdr)->errlen, "vmod file failure: " fmt, \
+		 __VA_ARGS__)
+
+#define INIT_SLEEP_INTERVAL 0.001
+#define ERRMSG_LEN 128
+#define NO_ERR ("No error")
+
 struct file_info {
 	unsigned	magic;
 #define FILE_INFO_MAGIC 0x46ebec3d
 	struct timespec	mtime;
+	char		*path;
+	size_t		len;
 	dev_t		dev;
 	ino_t		ino;
 };
 
+#define RDR_INITIALIZED	(1 << 0)
+#define RDR_ERROR	(1 << 1)
+#define RDR_MAPPED	(1 << 2)
+#define RDR_TIMER_INIT	(1 << 3)
+
 struct VPFX(file_reader) {
 	unsigned		magic;
 #define FILE_READER_MAGIC 0x08d18e5b
+	timer_t			timerid;
 	struct file_info	*info;
 	char			*vcl_name;
-	char			*path;
 	char			*addr;
-	size_t			len;
-	VCL_DURATION		ttl;
-	VCL_TIME		t_expire;
+	char			*errbuf;
+	size_t			errlen;
+	int			flags;
 };
 
-static inline int
-do_stat(VRT_CTX, struct VPFX(file_reader) *rdr, struct stat *st,
-	const char *method)
-{
-	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
-	CHECK_OBJ_NOTNULL(rdr, FILE_READER_MAGIC);
-	AN(st);
-	
-	errno = 0;
-	if (stat(rdr->path, st) != 0) {
-		VFAIL(ctx, "%s.%s(): cannot read info about %s: %s",
-		      rdr->vcl_name, method,  rdr->path, vstrerror(errno));
-		return (-1);
-	}
-
-	if (!S_ISREG(st->st_mode)) {
-		VFAIL(ctx, "%s.%s(): %s is not a regular file", rdr->vcl_name,
-		      method, rdr->path);
-		return (-1);
-	}
-	return (0);
-}
-
-static int
-update_map(VRT_CTX, struct VPFX(file_reader) *rdr, struct stat *st,
-	   const char *method)
+static void
+check(union sigval val)
 {
+	struct VPFX(file_reader) *rdr;
 	struct file_info *info;
+	struct stat st;
 	int fd;
 	void *addr;
 
-	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
-	CHECK_OBJ_NOTNULL(rdr, FILE_READER_MAGIC);
+	CAST_OBJ_NOTNULL(rdr, val.sival_ptr, FILE_READER_MAGIC);
 	CHECK_OBJ_NOTNULL(rdr->info, FILE_INFO_MAGIC);
-	AN(st);
 	info = rdr->info;
+	AN(rdr->vcl_name);
+	AN(rdr->errbuf);
+	AN(info->path);
+
+	errno = 0;
+	if (stat(info->path, &st) != 0) {
+		VERRMSG(rdr, "%s: cannot read info about %s: %s", rdr->vcl_name,
+			info->path, vstrerror(errno));
+		VSL(SLT_Error, 0, rdr->errbuf);
+		rdr->flags |= RDR_ERROR;
+		return;
+	}
+
+	if (!S_ISREG(st.st_mode)) {
+		VERRMSG(rdr, "%s: %s is not a regular file", rdr->vcl_name,
+			info->path);
+		VSL(SLT_Error, 0, rdr->errbuf);
+		rdr->flags |= RDR_ERROR;
+		return;
+	}
+
+	if ((rdr->flags & (RDR_INITIALIZED | RDR_MAPPED))
+	    && info->mtime.tv_sec == st.st_mtim.tv_sec
+	    && info->mtime.tv_nsec == st.st_mtim.tv_nsec
+	    && info->dev == st.st_dev && info->ino == st.st_ino) {
+		AN(rdr->addr);
+		return;
+	}
+
+	if (rdr->flags & RDR_MAPPED) {
+		AN(rdr->addr);
+		if (munmap(rdr->addr, info->len) != 0) {
+			VERRMSG(rdr, "%s: unmap failed: %s", rdr->vcl_name,
+				vstrerror(errno));
+			VSL(SLT_Error, 0, rdr->errbuf);
+			rdr->flags |= RDR_ERROR;
+			return;
+		}
+	}
+	rdr->flags &= ~RDR_MAPPED;
 
 	errno = 0;
-	if ((fd = open(rdr->path, O_RDWR)) < 0) {
-		VFAIL(ctx, "%s.%s(): cannot open %s: %s", rdr->vcl_name, method,
-		      rdr->path, vstrerror(errno));
-		return (-1);
+	if ((fd = open(info->path, O_RDWR)) < 0) {
+		VERRMSG(rdr, "%s: cannot open %s: %s", rdr->vcl_name,
+			info->path, vstrerror(errno));
+		VSL(SLT_Error, 0, rdr->errbuf);
+		rdr->flags |= RDR_ERROR;
+		return;
 	}
 
 	errno = 0;
-	if ((addr = mmap(NULL, st->st_size + 1, PROT_READ|PROT_WRITE,
+	if ((addr = mmap(NULL, st.st_size + 1, PROT_READ|PROT_WRITE,
 			 MAP_PRIVATE, fd, 0)) == MAP_FAILED) {
-		VFAIL(ctx, "%s.%s(): could not map %s: %s", rdr->vcl_name,
-		      method, rdr->path, vstrerror(errno));
+		VERRMSG(rdr, "%s: could not map %s: %s", rdr->vcl_name,
+			info->path, vstrerror(errno));
+		VSL(SLT_Error, 0, rdr->errbuf);
+		rdr->flags |= RDR_ERROR;
 		closefd(&fd);
-		return (-1);
+		return;
 	}
 	closefd(&fd);
+	AN(addr);
+	rdr->flags |= RDR_MAPPED;
 
 	/*
 	 * Add a terminating null byte, so that the mapped file can be
 	 * used as a VCL_STRING or a C string.
 	 */
-	*((char *)(addr + st->st_size)) = '\0';
+	*((char *)(addr + st.st_size)) = '\0';
 
-	info->mtime.tv_sec = st->st_mtim.tv_sec;
-	info->mtime.tv_nsec = st->st_mtim.tv_nsec;
-	info->dev = st->st_dev;
-	info->ino = st->st_ino;
+	info->mtime.tv_sec = st.st_mtim.tv_sec;
+	info->mtime.tv_nsec = st.st_mtim.tv_nsec;
+	info->dev = st.st_dev;
+	info->ino = st.st_ino;
+	info->len = st.st_size + 1;
 
 	rdr->addr = addr;
-	rdr->len = st->st_size + 1;
-	return (0);
+	rdr->flags &= ~RDR_ERROR;
+	strcpy(rdr->errbuf, NO_ERR);
+	rdr->flags |= RDR_INITIALIZED;
+	return;
 }
 
 VCL_VOID
@@ -144,7 +190,9 @@ vmod_reader__init(VRT_CTX, struct VPFX(file_reader) **rdrp,
 {
 	struct VPFX(file_reader) *rdr;
 	struct file_info *info;
-	struct stat st;
+	struct sigevent sigev;
+	timer_t timerid;
+	struct itimerspec timerspec;
 
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
 	AN(rdrp);
@@ -156,6 +204,10 @@ vmod_reader__init(VRT_CTX, struct VPFX(file_reader) **rdrp,
 		VFAIL(ctx, "new %s: name is NULL", vcl_name);
 		return;
 	}
+	if (*name == '\0') {
+		VFAIL(ctx, "new %s: name is empty", vcl_name);
+		return;
+	}
 	if (ttl <= 0) {
 		VFAIL(ctx, "new %s: ttl %.03f must be > 0", vcl_name, ttl);
 		return;
@@ -177,16 +229,66 @@ vmod_reader__init(VRT_CTX, struct VPFX(file_reader) **rdrp,
 		return;
 	}
 
+	rdr->errlen = ERRMSG_LEN + strlen(name) + strlen(vcl_name);
+	errno = 0;
+	rdr->errbuf = malloc(rdr->errlen);
+	if (rdr->errbuf == NULL) {
+		VFAIL(ctx, "new %s: allocating error message buffer: %s",
+		      vcl_name, vstrerror(errno));
+		return;
+	}
+
 	rdr->info = info;
 	rdr->vcl_name = strdup(vcl_name);
-	rdr->path = strdup(name);
-	rdr->ttl = ttl;
-	rdr->t_expire = ctx->now + ttl;
+	info->path = strdup(name);
+
+	memset(&sigev, 0, sizeof(sigev));
+	sigev.sigev_notify = SIGEV_THREAD;
+	sigev.sigev_notify_function = check;
+	sigev.sigev_value.sival_ptr = rdr;
+
+	errno = 0;
+	if (timer_create(CLOCK_MONOTONIC, &sigev, &timerid) != 0) {
+		VFAIL(ctx, "new %s: cannot create update timer: %s", vcl_name,
+		      vstrerror(errno));
+		return;
+	}
+	rdr->timerid = timerid;
 
-	if (do_stat(ctx, rdr, &st, "new") != 0)
+	timerspec.it_value.tv_sec = 0;
+	timerspec.it_value.tv_nsec = 1;
+	timerspec.it_interval.tv_sec = (time_t)ttl;
+	assert(timerspec.it_interval.tv_sec - ttl < 1.);
+	timerspec.it_interval.tv_nsec
+		= (long)(1e9 * (timerspec.it_interval.tv_sec - ttl));
+
+	errno = 0;
+	if (timer_settime(timerid, 0, &timerspec, NULL) != 0) {
+		VFAIL(ctx, "new %s: cannot start update timer: %s", vcl_name,
+		      vstrerror(errno));
 		return;
-	if (update_map(ctx, rdr, &st, "new") != 0)
+	}
+	rdr->flags |= RDR_TIMER_INIT;
+
+
+	AZ(rdr->addr);
+	AZ(rdr->info->mtime.tv_sec);
+	AZ(rdr->info->mtime.tv_nsec);
+	AZ(rdr->flags & (RDR_INITIALIZED | RDR_ERROR));
+	do {
+		VTIM_sleep(INIT_SLEEP_INTERVAL);
+	} while ((rdr->flags & (RDR_INITIALIZED | RDR_ERROR)) == 0);
+
+	if (rdr->flags & RDR_ERROR) {
+		AN(strcmp(rdr->errbuf, NO_ERR));
+		VFAIL(ctx, "new %s: %s", vcl_name, rdr->errbuf);
 		return;
+	}
+
+	AN(rdr->flags & RDR_MAPPED);
+	AN(rdr->addr);
+	AN(rdr->info->mtime.tv_sec);
+	AN(rdr->info->mtime.tv_nsec);
 
 	*rdrp = rdr;
 }
@@ -200,53 +302,56 @@ vmod_reader__fini(struct VPFX(file_reader) **rdrp)
 		return;
 	TAKE_OBJ_NOTNULL(rdr, rdrp, FILE_READER_MAGIC);
 
-	errno = 0;
-	if (munmap(rdr->addr, rdr->len) != 0)
-		VSL(SLT_Error, 0, "unmap failed in %s finalization: %s",
-		    rdr->vcl_name, vstrerror(errno));
+	if (rdr->flags & RDR_TIMER_INIT) {
+		AN(rdr->vcl_name);
+
+		errno = 0;
+		if (timer_delete(rdr->timerid) != 0)
+			VSL(SLT_Error, 0, "vmod file %s finalization: "
+			    "cannot delete timer: %s", rdr->vcl_name,
+			    vstrerror(errno));
+	}
+
+	if (rdr->flags & RDR_MAPPED) {
+		CHECK_OBJ_NOTNULL(rdr->info, FILE_INFO_MAGIC);
+		AN(rdr->addr);
+		AN(rdr->vcl_name);
+
+		errno = 0;
+		if (munmap(rdr->addr, rdr->info->len) != 0)
+			VSL(SLT_Error, 0, "vmod file %s finalization: "
+			    "unmap failed: %s", rdr->vcl_name,
+			    vstrerror(errno));
+	}
 
 	if (rdr->info != NULL) {
 		CHECK_OBJ(rdr->info, FILE_INFO_MAGIC);
+		if (rdr->info->path != NULL)
+			free(rdr->info->path);
 		FREE_OBJ(rdr->info);
 	}
 	if (rdr->vcl_name != NULL)
 		free(rdr->vcl_name);
-	if (rdr->path != NULL)
-		free(rdr->path);
+	if (rdr->errbuf != NULL)
+		free(rdr->errbuf);
 	FREE_OBJ(rdr);
 }
 
 VCL_STRING
 vmod_reader_get(VRT_CTX, struct VPFX(file_reader) *rdr)
 {
-	struct file_info *info;
-	struct stat st;
-	double intervals, whole, frac;
-
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
 	CHECK_OBJ_NOTNULL(rdr, FILE_READER_MAGIC);
-	CHECK_OBJ_NOTNULL(rdr->info, FILE_INFO_MAGIC);
-	AN(rdr->addr);
-	info = rdr->info;
 
-	if (ctx->now <= rdr->t_expire)
+	if ((rdr->flags & RDR_ERROR) == 0) {
+		AN(rdr->addr);
+		AN(rdr->flags & RDR_MAPPED);
 		return (rdr->addr);
+	}
 
-	if (do_stat(ctx, rdr, &st, "get") != 0)
-		return (NULL);
-
-	if (info->mtime.tv_sec == st.st_mtim.tv_sec
-	    && info->mtime.tv_nsec == st.st_mtim.tv_nsec
-	    && info->dev == st.st_dev && info->ino == st.st_ino)
-		return (rdr->addr);
-
-	if (update_map(ctx, rdr, &st, "get") != 0)
-		return (NULL);
-
-	intervals = (ctx->now - rdr->t_expire) / rdr->ttl;
-	frac = modf(intervals, &whole);
-	rdr->t_expire = ctx->now + (rdr->ttl * (1. - frac));
-	return (rdr->addr);
+	AN(strcmp(rdr->errbuf, NO_ERR));
+	VFAIL(ctx, "%s.get(): %s", rdr->vcl_name, rdr->errbuf);
+	return (NULL);
 }
 
 VCL_STRING