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Adopted LRU from https://github.com/cluck, tested, fixed some issues (fix of issue#20) #22

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Adopted LRU from https://github.com/cluck, tested, fixed some issues (fix of issue#20) #22

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9d360bc
adopted LRU from https://github.com/cluck, tested, fixed some issues,…
wwwenca Sep 30, 2017
4ba76f8
fixed copilation error without ZERO_COPY, namings, added critical sec…
wwwenca Sep 30, 2017
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72 changes: 52 additions & 20 deletions sparsebundlefs.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -39,10 +39,13 @@
#include <iostream>
#include <limits>
#include <map>
#include <list>
#include <sstream>
#include <streambuf>
#include <string>
#include <vector>
#include <pthread.h>


#include <fuse.h>

Expand All @@ -51,6 +54,8 @@
using namespace std;

static const char image_path[] = "/sparsebundle.dmg";
unsigned int max_open_files = 128;


struct sparsebundle_t {
char *path;
Expand All @@ -60,6 +65,7 @@ struct sparsebundle_t {
off_t times_opened;
#if FUSE_SUPPORTS_ZERO_COPY
map<string, int> open_files;
list<string> lru_files;
#endif
};

Expand Down Expand Up @@ -245,23 +251,53 @@ static int sparsebundle_read(const char *path, char *buffer, size_t length, off_
}

#if FUSE_SUPPORTS_ZERO_COPY
static void sparsebundle_cleanup_open_files()
{
sparsebundle_t *sparsebundle = sparsebundle_current();

syslog(LOG_DEBUG, "lru size: %zu", sparsebundle->lru_files.size());


if (sparsebundle->lru_files.size() >= max_open_files) {
syslog(LOG_DEBUG, "too many open files, closing least recently opened bands");
while (sparsebundle->lru_files.size() * 2 >= max_open_files) {
const char* lru_path = sparsebundle->lru_files.back().c_str();
int c = close(sparsebundle->open_files[lru_path]);
syslog(LOG_DEBUG, "closing %s, result %i", lru_path, c);
sparsebundle->open_files.erase(lru_path);
sparsebundle->lru_files.pop_back(); // be sure to have this as a last line, otherwise it screws lru_path string
}
}
}

pthread_mutex_t lru_lock;

static int sparsebundle_read_buf_prepare_file(const char *path)
{
sparsebundle_t *sparsebundle = sparsebundle_current();

int fd = -1;
//critical section
pthread_mutex_lock(&lru_lock);
syslog(LOG_DEBUG, "thread %zu entered critical section", (unsigned int)pthread_self());
map<string, int>::const_iterator iter = sparsebundle->open_files.find(path);
if (iter != sparsebundle->open_files.end()) {
fd = iter->second;
sparsebundle->lru_files.remove(path); //remove path from LRU - we will store it on top in the end
} else {
syslog(LOG_DEBUG, "file %s not opened yet, opening", path);
sparsebundle_cleanup_open_files();
fd = open(path, O_RDONLY);
sparsebundle->open_files[path] = fd;
}
sparsebundle->lru_files.push_front(path); // store the path on the top of LRU
syslog(LOG_DEBUG, "thread %zu leaving critical section", (unsigned int)pthread_self());
pthread_mutex_unlock(&lru_lock);
//end of critical section

return fd;
}

static int sparsebundle_read_buf_process_band(const char *band_path, size_t length, off_t offset, void *read_data)
{
ssize_t read = 0;
Expand Down Expand Up @@ -305,15 +341,22 @@ static void sparsebundle_read_buf_close_files()
{
sparsebundle_t *sparsebundle = sparsebundle_current();

syslog(LOG_DEBUG, "closing %u open file descriptor(s)", sparsebundle->open_files.size());
syslog(LOG_DEBUG, "closing %zu open file(s)", sparsebundle->lru_files.size());

//critical section
pthread_mutex_lock(&lru_lock);
syslog(LOG_DEBUG, "thread %zu entered critical section", (unsigned int)pthread_self());

map<string, int>::iterator iter;
for(iter = sparsebundle->open_files.begin(); iter != sparsebundle->open_files.end(); ++iter) {
close(iter->second);
syslog(LOG_DEBUG, "closed %s", iter->first.c_str());
while (sparsebundle->lru_files.size() > 0) {
const char* path = sparsebundle->lru_files.back().c_str();
close(sparsebundle->open_files[path]);
sparsebundle->open_files.erase(path);
sparsebundle->lru_files.pop_back();
}

sparsebundle->open_files.clear();
syslog(LOG_DEBUG, "thread %zu leaving critical section", (unsigned int)pthread_self());
pthread_mutex_unlock(&lru_lock);
//end of critical section
}

static int sparsebundle_read_buf(const char *path, struct fuse_bufvec **bufp,
Expand All @@ -332,18 +375,6 @@ static int sparsebundle_read_buf(const char *path, struct fuse_bufvec **bufp,
syslog(LOG_DEBUG, "asked to read %zu bytes at offset %ju using zero-copy read",
length, uintmax_t(offset));

static struct rlimit fd_limit;
static bool fd_limit_computed = false;
if (!fd_limit_computed) {
getrlimit(RLIMIT_NOFILE, &fd_limit);
fd_limit_computed = true;
}

sparsebundle_t *sparsebundle = sparsebundle_current();
if (sparsebundle->open_files.size() + 1 >= fd_limit.rlim_cur) {
syslog(LOG_DEBUG, "hit max number of file descriptors");
sparsebundle_read_buf_close_files();
}

ret = sparsebundle_iterate_bands(path, length, offset, &read_ops);
if (ret < 0)
Expand Down Expand Up @@ -452,7 +483,7 @@ static off_t read_size(const string &str)

int main(int argc, char **argv)
{
openlog("sparsebundlefs", LOG_CONS | LOG_PERROR, LOG_USER);
openlog("sparsebundlefs", LOG_CONS | LOG_PERROR | LOG_PID, LOG_USER);
setlogmask(~(LOG_MASK(LOG_DEBUG)));

struct sparsebundle_t sparsebundle = {};
Expand Down Expand Up @@ -516,3 +547,4 @@ int main(int argc, char **argv)

return fuse_main(args.argc, args.argv, &sparsebundle_filesystem_operations, &sparsebundle);
}