[libvirt PATCH v2 05/16] qemu: implement basic virFileCache for nbdkit caps

[Jonathon Jongsma]

Preparatory step for caching nbdkit capabilities. This patch implements
the newData and isValid virFileCacheHandlers callback functions.

Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>
---
 src/qemu/qemu_nbdkit.c | 91 ++++++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_nbdkit.h |  3 ++
 2 files changed, 94 insertions(+)

diff --git a/src/qemu/qemu_nbdkit.c b/src/qemu/qemu_nbdkit.c
index 0ea1b754cd..3faa16674a 100644
--- a/src/qemu/qemu_nbdkit.c
+++ b/src/qemu/qemu_nbdkit.c
@@ -263,3 +263,94 @@ qemuNbdkitCapsSet(qemuNbdkitCaps *nbdkitCaps,
 {
     ignore_value(virBitmapSetBit(nbdkitCaps->flags, flag));
 }
+
+
+static bool
+virNbkditCapsCheckModdir(const char *moddir,
+                         time_t expectedMtime)
+{
+    time_t mtime = getDirMtime(moddir);
+
+    if (mtime != expectedMtime) {
+        VIR_DEBUG("Outdated capabilities for nbdkit: module "
+                  "directory '%s' changed (%lld vs %lld)",
+                  moddir,
+                  (long long)mtime, (long long)expectedMtime);
+        return false;
+    }
+    return true;
+}
+
+
+static bool
+virNbdkitCapsIsValid(void *data,
+                     void *privData G_GNUC_UNUSED)
+{
+    qemuNbdkitCaps *nbdkitCaps = data;
+    struct stat st;
+
+    if (!nbdkitCaps->path)
+        return true;
+
+    if (!virNbkditCapsCheckModdir(NBDKIT_PLUGINDIR, nbdkitCaps->pluginDirMtime))
+        return false;
+    if (!virNbkditCapsCheckModdir(NBDKIT_FILTERDIR, nbdkitCaps->filterDirMtime))
+        return false;
+
+    if (nbdkitCaps->libvirtCtime != virGetSelfLastChanged() ||
+        nbdkitCaps->libvirtVersion != LIBVIR_VERSION_NUMBER) {
+        VIR_DEBUG("Outdated capabilities for '%s': libvirt changed "
+                  "(%lld vs %lld, %lu vs %lu)",
+                  nbdkitCaps->path,
+                  (long long)nbdkitCaps->libvirtCtime,
+                  (long long)virGetSelfLastChanged(),
+                  (unsigned long)nbdkitCaps->libvirtVersion,
+                  (unsigned long)LIBVIR_VERSION_NUMBER);
+        return false;
+    }
+
+    if (stat(nbdkitCaps->path, &st) < 0) {
+        VIR_DEBUG("Failed to stat nbdkit binary '%s': %s",
+                  nbdkitCaps->path,
+                  g_strerror(errno));
+        return false;
+    }
+
+    if (st.st_ctime != nbdkitCaps->ctime) {
+        VIR_DEBUG("Outdated capabilities for '%s': nbdkit binary changed "
+                  "(%lld vs %lld)",
+                  nbdkitCaps->path,
+                  (long long)st.st_ctime, (long long)nbdkitCaps->ctime);
+        return false;
+    }
+
+    return true;
+}
+
+
+static void*
+virNbdkitCapsNewData(const char *binary,
+                     void *privData G_GNUC_UNUSED)
+{
+    qemuNbdkitCaps *caps = qemuNbdkitCapsNew(binary);
+    qemuNbdkitCapsQuery(caps);
+
+    return caps;
+}
+
+
+virFileCacheHandlers nbdkitCapsCacheHandlers = {
+    .isValid = virNbdkitCapsIsValid,
+    .newData = virNbdkitCapsNewData,
+    .loadFile = NULL,
+    .saveFile = NULL,
+    .privFree = NULL,
+};
+
+
+virFileCache*
+qemuNbdkitCapsCacheNew(const char *cachedir)
+{
+    g_autofree char *dir = g_build_filename(cachedir, "nbdkitcapabilities", NULL);
+    return virFileCacheNew(dir, "xml", &nbdkitCapsCacheHandlers);
+}
diff --git a/src/qemu/qemu_nbdkit.h b/src/qemu/qemu_nbdkit.h
index 4baf4d4d31..b65e76895b 100644
--- a/src/qemu/qemu_nbdkit.h
+++ b/src/qemu/qemu_nbdkit.h
@@ -25,6 +25,7 @@
 #include "virbitmap.h"
 #include "vircgroup.h"
 #include "vircommand.h"
+#include "virfilecache.h"
 #include "virstorageobj.h"
 #include "viruri.h"
 
@@ -43,6 +44,8 @@ qemuNbdkitCaps* qemuQueryNbdkitCaps(void);
 
 qemuNbdkitCaps* qemuNbdkitCapsNew(const char *path);
 
+virFileCache* qemuNbdkitCapsCacheNew(const char *cachedir);
+
 bool qemuNbdkitCapsGet(qemuNbdkitCaps *nbdkitCaps, qemuNbdkitCapsFlags flag);
 
 void qemuNbdkitCapsSet(qemuNbdkitCaps *nbdkitCaps, qemuNbdkitCapsFlags flag);
-- 
2.37.1