X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=store.cc;h=8f2c8b328c2d7cacea3ca4c3683993532d1a7980;hb=87c6a5ed4ec515c2e154f98529c1d2f077d2a7e4;hp=ce54e8717cb195bab45fe8b916ab87eb79cc4e33;hpb=5c10647d667fc4408b73402db9247181a54a57ad;p=cumulus.git

diff --git a/store.cc b/store.cc
index ce54e87..8f2c8b3 100644
--- a/store.cc
+++ b/store.cc
@@ -10,11 +10,15 @@
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/resource.h>
+#include <sys/wait.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <time.h>
 
+#include <algorithm>
 #include <list>
+#include <map>
 #include <set>
 #include <string>
 #include <iostream>
@@ -22,25 +26,104 @@
 #include "store.h"
 #include "ref.h"
 
+using std::max;
 using std::list;
+using std::map;
 using std::set;
 using std::string;
 
+/* Default filter program is bzip2 */
+const char *filter_program = "bzip2 -c";
+const char *filter_extension = ".bz2";
+
+static void cloexec(int fd)
+{
+    long flags = fcntl(fd, F_GETFD);
+
+    if (flags < 0)
+        return;
+
+    fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
+}
+
 Tarfile::Tarfile(const string &path, const string &segment)
     : size(0),
       segment_name(segment)
 {
-    if (tar_open(&t, (char *)path.c_str(), NULL, O_WRONLY | O_CREAT, 0600,
-                 TAR_VERBOSE | TAR_GNU) == -1)
+    real_fd = open(path.c_str(), O_WRONLY | O_CREAT, 0600);
+    if (real_fd < 0)
+        throw IOException("Error opening output file");
+
+    filter_fd = spawn_filter(real_fd);
+
+    if (tar_fdopen(&t, filter_fd, (char *)path.c_str(), NULL,
+                   O_WRONLY | O_CREAT, 0666, TAR_VERBOSE | TAR_GNU) == -1)
         throw IOException("Error opening Tarfile");
 }
 
 Tarfile::~Tarfile()
 {
+    /* Close the tar file... */
     tar_append_eof(t);
 
     if (tar_close(t) != 0)
         throw IOException("Error closing Tarfile");
+
+    /* ...and wait for filter process to finish. */
+    int status;
+    waitpid(filter_pid, &status, 0);
+
+    if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+        throw IOException("Filter process error");
+    }
+
+    close(real_fd);
+}
+
+/* Launch a child process which can act as a filter (compress, encrypt, etc.)
+ * on the TAR output.  The file descriptor to which output should be written
+ * must be specified; the return value is the file descriptor which will be
+ * attached to the standard input of the filter program. */
+int Tarfile::spawn_filter(int fd_out)
+{
+    int fds[2];
+
+    /* Create a pipe for communicating with the filter process. */
+    if (pipe(fds) < 0) {
+        throw IOException("Unable to create pipe for filter");
+    }
+
+    /* Create a child process which can exec() the filter program. */
+    filter_pid = fork();
+    if (filter_pid < 0)
+        throw IOException("Unable to fork filter process");
+
+    if (filter_pid > 0) {
+        /* Parent process */
+        close(fds[0]);
+        cloexec(fds[1]);
+    } else {
+        /* Child process.  Rearrange file descriptors.  stdin is fds[0], stdout
+         * is fd_out, stderr is unchanged. */
+        close(fds[1]);
+
+        if (dup2(fds[0], 0) < 0)
+            exit(1);
+        close(fds[0]);
+
+        if (dup2(fd_out, 1) < 0)
+            exit(1);
+        close(fd_out);
+
+        /* Exec the filter program. */
+        execlp("/bin/sh", "/bin/sh", "-c", filter_program, NULL);
+
+        /* Should not reach here except for error cases. */
+        fprintf(stderr, "Could not exec filter: %m\n");
+        exit(1);
+    }
+
+    return fds[1];
 }
 
 void Tarfile::write_object(int id, const char *data, size_t len)
@@ -91,8 +174,30 @@ void Tarfile::internal_write_object(const string &path,
     size += blocks * T_BLOCKSIZE;
 }
 
+/* Estimate the size based on the size of the actual output file on disk.
+ * However, it might be the case that the filter program is buffering all its
+ * data, and might potentially not write a single byte until we have closed
+ * our end of the pipe.  If we don't do so until we see data written, we have
+ * a problem.  So, arbitrarily pick an upper bound on the compression ratio
+ * that the filter will achieve (128:1), and return a size estimate which is
+ * the larger of a) bytes actually seen written to disk, and b) input
+ * bytes/128. */
+size_t Tarfile::size_estimate()
+{
+    struct stat statbuf;
+
+    if (fstat(real_fd, &statbuf) == 0)
+        return max((int64_t)statbuf.st_size, (int64_t)(size / 128));
+
+    /* Couldn't stat the file on disk, so just return the actual number of
+     * bytes, before compression. */
+    return size;
+}
+
 static const size_t SEGMENT_SIZE = 4 * 1024 * 1024;
 
+static map<string, int64_t> group_sizes;
+
 ObjectReference TarSegmentStore::write_object(const char *data, size_t len,
                                               const std::string &group)
 {
@@ -106,6 +211,7 @@ ObjectReference TarSegmentStore::write_object(const char *data, size_t len,
         segment->name = generate_uuid();
 
         string filename = path + "/" + segment->name + ".tar";
+        filename += filter_extension;
         segment->file = new Tarfile(filename, segment->name);
 
         segment->count = 0;
@@ -122,6 +228,8 @@ ObjectReference TarSegmentStore::write_object(const char *data, size_t len,
     segment->file->write_object(id, data, len);
     segment->count++;
 
+    group_sizes[group] += len;
+
     ObjectReference ref(segment->name, id_buf);
 
     // If this segment meets or exceeds the size target, close it so that
@@ -138,11 +246,18 @@ void TarSegmentStore::sync()
         close_segment(segments.begin()->first);
 }
 
+void TarSegmentStore::dump_stats()
+{
+    printf("Data written:\n");
+    for (map<string, int64_t>::iterator i = group_sizes.begin();
+         i != group_sizes.end(); ++i) {
+        printf("    %s: %lld\n", i->first.c_str(), i->second);
+    }
+}
+
 void TarSegmentStore::close_segment(const string &group)
 {
     struct segment_info *segment = segments[group];
-    fprintf(stderr, "Closing segment group %s (%s)\n",
-            group.c_str(), segment->name.c_str());
 
     delete segment->file;
     segments.erase(segments.find(group));