Implement the core API to suspend/resume the host

Add the core functions that implement the functionality of the API.
Suspend is done by using an asynchronous mechanism so that we can return
the status to the caller before the host gets suspended. This asynchronous
operation is achieved by suspending the host in a separate thread of
execution. However, returning the status to the caller is only best-effort,
but not guaranteed.

To resume the host, an RTC alarm is set up (based on how long we want to
suspend) before suspending the host. When this alarm fires, the host
gets woken up.

Suspend-to-RAM operation on a host running Linux can take upto more than 20
seconds, depending on the load of the system. (Freezing of tasks, an operation
preceding any suspend operation, is given up after a 20 second timeout).
And Suspend-to-Disk can take even more time, considering the time required
for compaction, creating the memory image and writing it to disk etc.
So, we do not allow the user to specify a suspend duration of less than 60
seconds, to be on the safer side, since we don't want to prematurely declare
failure when we only had to wait for some more time.

po/POTFILES.in

@@ -130,6 +130,7 @@ src/util/virnetdevbridge.c
 src/util/virnetdevmacvlan.c
 src/util/virnetdevtap.c
 src/util/virnetdevvportprofile.c
+src/util/virnodesuspend.c
 src/util/virpidfile.c
 src/util/virsocketaddr.c
 src/util/virterror.c

src/Makefile.am

@@ -85,6 +85,7 @@ UTIL_SOURCES =							\
 		util/util.c util/util.h				\
 		util/viraudit.c util/viraudit.h			\
 		util/virfile.c util/virfile.h			\
+		util/virnodesuspend.c util/virnodesuspend.h	\
 		util/virpidfile.c util/virpidfile.h		\
 		util/xml.c util/xml.h				\
 		util/virterror.c util/virterror_internal.h	\

src/libvirt.c

@@ -43,6 +43,7 @@
 #include "conf.h"
 #include "rpc/virnettlscontext.h"
 #include "command.h"
+#include "virnodesuspend.h"
 
 #ifndef WITH_DRIVER_MODULES
 # ifdef WITH_TEST
@@ -399,7 +400,8 @@ virInitialize(void)
 
     if (virThreadInitialize() < 0 ||
         virErrorInitialize() < 0 ||
-        virRandomInitialize(time(NULL) ^ getpid()))
+        virRandomInitialize(time(NULL) ^ getpid()) ||
+        virNodeSuspendInit() < 0)
         return -1;
 
     gcry_control(GCRYCTL_SET_THREAD_CBS, &virTLSThreadImpl);

src/libvirt_private.syms

@@ -1329,6 +1329,11 @@ virNetTLSContextNewServer;
 virNetTLSContextNewServerPath;
 
 
+# virnodesuspend.h
+nodeSuspendForDuration;
+virNodeSuspendInit;
+
+
 # virpidfile.h
 virPidFileAcquire;
 virPidFileAcquirePath;

src/lxc/lxc_driver.c

@@ -56,6 +56,7 @@
 #include "domain_nwfilter.h"
 #include "network/bridge_driver.h"
 #include "virnetdev.h"
+#include "virnodesuspend.h"
 
 #define VIR_FROM_THIS VIR_FROM_LXC
 
@@ -3922,6 +3923,7 @@ static virDriver lxcDriver = {
     .domainEventDeregisterAny = lxcDomainEventDeregisterAny, /* 0.8.0 */
     .domainOpenConsole = lxcDomainOpenConsole, /* 0.8.6 */
     .isAlive = lxcIsAlive, /* 0.9.8 */
+    .nodeSuspendForDuration = nodeSuspendForDuration, /* 0.9.8 */
 };
 
 static virStateDriver lxcStateDriver = {

src/qemu/qemu_driver.c

@@ -88,6 +88,7 @@
 #include "locking/lock_manager.h"
 #include "locking/domain_lock.h"
 #include "virkeycode.h"
+#include "virnodesuspend.h"
 
 #define VIR_FROM_THIS VIR_FROM_QEMU
 
@@ -10913,6 +10914,7 @@ static virDriver qemuDriver = {
     .domainBlockJobSetSpeed = qemuDomainBlockJobSetSpeed, /* 0.9.4 */
     .domainBlockPull = qemuDomainBlockPull, /* 0.9.4 */
     .isAlive = qemuIsAlive, /* 0.9.8 */
+    .nodeSuspendForDuration = nodeSuspendForDuration, /* 0.9.8 */
 };
 
 

src/uml/uml_driver.c

@@ -62,6 +62,7 @@
 #include "fdstream.h"
 #include "configmake.h"
 #include "virnetdevtap.h"
+#include "virnodesuspend.h"
 
 #define VIR_FROM_THIS VIR_FROM_UML
 
@@ -2604,6 +2605,7 @@ static virDriver umlDriver = {
     .domainEventDeregisterAny = umlDomainEventDeregisterAny, /* 0.9.4 */
     .domainOpenConsole = umlDomainOpenConsole, /* 0.8.6 */
     .isAlive = umlIsAlive, /* 0.9.8 */
+    .nodeSuspendForDuration = nodeSuspendForDuration, /* 0.9.8 */
 };
 
 static int

src/util/virnodesuspend.c

+/*
+ * virnodesuspend.c: Support for suspending a node (host machine)
+ *
+ * Copyright (C) 2011 Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
+ *
+ */
+
+#include <config.h>
+#include "virnodesuspend.h"
+
+#include "command.h"
+#include "threads.h"
+#include "datatypes.h"
+
+#include "memory.h"
+#include "logging.h"
+#include "virterror_internal.h"
+
+#define VIR_FROM_THIS VIR_FROM_NONE
+
+#define virNodeSuspendError(code, ...)                                     \
+        virReportErrorHelper(VIR_FROM_NONE, code, __FILE__,                \
+                             __FUNCTION__, __LINE__, __VA_ARGS__)
+
+
+#define SUSPEND_DELAY 10 /* in seconds */
+
+/* Give sufficient time for performing the suspend operation on the host */
+#define MIN_TIME_REQ_FOR_SUSPEND 60 /* in seconds */
+
+/*
+ * Bitmask to hold the Power Management features supported by the host,
+ * such as Suspend-to-RAM, Suspend-to-Disk, Hybrid-Suspend etc.
+ */
+static unsigned int hostPMFeatures;
+
+virMutex virNodeSuspendMutex;
+
+static bool aboutToSuspend;
+
+static void virNodeSuspendLock(void)
+{
+    virMutexLock(&virNodeSuspendMutex);
+}
+
+static void virNodeSuspendUnlock(void)
+{
+    virMutexUnlock(&virNodeSuspendMutex);
+}
+
+
+/**
+ * virNodeSuspendInit:
+ *
+ * Get the system-wide sleep states supported by the host, such as
+ * Suspend-to-RAM, Suspend-to-Disk, or Hybrid-Suspend, so that a request
+ * to suspend/hibernate the host can be handled appropriately based on
+ * this information.
+ *
+ * Returns 0 if successful, and -1 in case of error.
+ */
+int virNodeSuspendInit(void)
+{
+
+    if (virMutexInit(&virNodeSuspendMutex) < 0)
+        return -1;
+
+    /* Get the power management capabilities supported by the host */
+    hostPMFeatures = 0;
+    if (virGetPMCapabilities(&hostPMFeatures) < 0) {
+        if (geteuid() == 0)
+            VIR_ERROR(_("Failed to get host power management features"));
+    }
+
+    return 0;
+}
+
+
+/**
+ * virNodeSuspendSetNodeWakeup:
+ * @alarmTime: time in seconds from now, at which the RTC alarm has to be set.
+ *
+ * Set up the RTC alarm to the specified time.
+ * Return 0 on success, -1 on failure.
+ */
+static int virNodeSuspendSetNodeWakeup(unsigned long long alarmTime)
+{
+    virCommandPtr setAlarmCmd;
+    int ret = -1;
+
+    if (alarmTime <= MIN_TIME_REQ_FOR_SUSPEND) {
+        virNodeSuspendError(VIR_ERR_INVALID_ARG, "%s", _("Suspend duration is too short"));
+        return -1;
+    }
+
+    setAlarmCmd = virCommandNewArgList("rtcwake", "-m", "no", "-s", NULL);
+    virCommandAddArgFormat(setAlarmCmd, "%lld", alarmTime);
+
+    if (virCommandRun(setAlarmCmd, NULL) < 0)
+        goto cleanup;
+
+    ret = 0;
+
+cleanup:
+    virCommandFree(setAlarmCmd);
+    return ret;
+}
+
+/**
+ * virNodeSuspend:
+ * @cmdString: pointer to the command string this thread has to execute.
+ *
+ * Actually perform the suspend operation by invoking the command.
+ * Give a short delay before executing the command so as to give a chance
+ * to virNodeSuspendForDuration() to return the status to the caller.
+ * If we don't give this delay, that function will not be able to return
+ * the status, since the suspend operation would have begun and hence no
+ * data can be sent through the connection to the caller. However, with
+ * this delay added, the status return is best-effort only.
+ */
+static void virNodeSuspend(void *cmdString)
+{
+    virCommandPtr suspendCmd = virCommandNew((char *)cmdString);
+
+    VIR_FREE(cmdString);
+
+    /*
+     * Delay for sometime so that the function nodeSuspendForDuration()
+     * can return the status to the caller.
+     */
+    sleep(SUSPEND_DELAY);
+    if (virCommandRun(suspendCmd, NULL) < 0)
+        VIR_WARN("Failed to suspend the host");
+
+    virCommandFree(suspendCmd);
+
+    /*
+     * Now that we have resumed from suspend or the suspend failed,
+     * reset 'aboutToSuspend' flag.
+     */
+    virNodeSuspendLock();
+    aboutToSuspend = false;
+    virNodeSuspendUnlock();
+}
+
+/**
+ * nodeSuspendForDuration:
+ * @conn: pointer to the hypervisor connection
+ * @target: the state to which the host must be suspended to -
+ *         VIR_NODE_SUSPEND_TARGET_MEM       (Suspend-to-RAM),
+ *         VIR_NODE_SUSPEND_TARGET_DISK      (Suspend-to-Disk),
+ *         VIR_NODE_SUSPEND_TARGET_HYBRID    (Hybrid-Suspend)
+ * @duration: the time duration in seconds, for which the host must be
+ *            suspended
+ * @flags: any flag values that might need to be passed; currently unused.
+ *
+ * Suspend the node (host machine) for the given duration of time in the
+ * specified state (such as Mem, Disk or Hybrid-Suspend). Attempt to resume
+ * the node after the time duration is complete.
+ *
+ * First, an RTC alarm is set appropriately to wake up the node from its
+ * sleep state. Then the actual node suspend operation is carried out
+ * asynchronously in another thread, after a short time delay so as to
+ * give enough time for this function to return status to its caller
+ * through the connection. However this returning of status is best-effort
+ * only, and should generally happen due to the short delay but might be
+ * missed if the machine suspends first.
+ *
+ * Returns 0 in case the node is going to be suspended after a short delay,
+ * -1 if suspending the node is not supported, or if a previous suspend
+ * operation is still in progress.
+ */
+int nodeSuspendForDuration(virConnectPtr conn ATTRIBUTE_UNUSED,
+                           unsigned int target,
+                           unsigned long long duration,
+                           unsigned int flags)
+{
+    static virThread thread;
+    char *cmdString = NULL;
+
+    virCheckFlags(0, -1);
+
+    /*
+     * Ensure that we are the only ones trying to suspend.
+     * Fail if somebody has already initiated a suspend.
+     */
+    virNodeSuspendLock();
+
+    if (aboutToSuspend) {
+        /* A suspend operation is already in progress */
+        virNodeSuspendUnlock();
+        return -1;
+    } else {
+        aboutToSuspend = true;
+    }
+
+    virNodeSuspendUnlock();
+
+    /* Check if the host supports the requested suspend target */
+    switch (target) {
+    case VIR_NODE_SUSPEND_TARGET_MEM:
+        if (hostPMFeatures & VIR_NODE_SUSPEND_TARGET_MEM) {
+            cmdString = strdup("pm-suspend");
+            if (cmdString == NULL) {
+                virReportOOMError();
+                goto cleanup;
+            }
+            break;
+        }
+        virNodeSuspendError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s", _("Suspend-to-RAM"));
+        goto cleanup;
+
+    case VIR_NODE_SUSPEND_TARGET_DISK:
+        if (hostPMFeatures & VIR_NODE_SUSPEND_TARGET_DISK) {
+            cmdString = strdup("pm-hibernate");
+            if (cmdString == NULL) {
+                virReportOOMError();
+                goto cleanup;
+            }
+            break;
+        }
+        virNodeSuspendError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s", _("Suspend-to-Disk"));
+        goto cleanup;
+
+    case VIR_NODE_SUSPEND_TARGET_HYBRID:
+        if (hostPMFeatures & VIR_NODE_SUSPEND_TARGET_HYBRID) {
+            cmdString = strdup("pm-suspend-hybrid");
+            if (cmdString == NULL) {
+                virReportOOMError();
+                goto cleanup;
+            }
+            break;
+        }
+        virNodeSuspendError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s", _("Hybrid-Suspend"));
+        goto cleanup;
+
+    default:
+        virNodeSuspendError(VIR_ERR_INVALID_ARG, "%s", _("Invalid suspend target"));
+        goto cleanup;
+    }
+
+    /* Just set the RTC alarm. Don't suspend yet. */
+    if (virNodeSuspendSetNodeWakeup(duration) < 0)
+        goto cleanup;
+
+    if (virThreadCreate(&thread, false, virNodeSuspend, (void *)cmdString) < 0) {
+        virNodeSuspendError(VIR_ERR_INTERNAL_ERROR, "%s",
+                        _("Failed to create thread to suspend the host\n"));
+        goto cleanup;
+    }
+
+    return 0;
+
+cleanup:
+    VIR_FREE(cmdString);
+    return -1;
+}

src/util/virnodesuspend.h

+/*
+ * virnodesuspend.h: Support for suspending a node (host machine)
+ *
+ * Copyright (C) 2011 Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
+ *
+ */
+
+
+#ifndef __VIR_NODE_SUSPEND_H__
+# define __VIR_NODE_SUSPEND_H__
+
+# include "internal.h"
+
+int nodeSuspendForDuration(virConnectPtr conn,
+                           unsigned int target,
+                           unsigned long long duration,
+                           unsigned int flags);
+
+int virNodeSuspendInit(void);
+
+
+#endif /* __VIR_NODE_SUSPEND_H__ */

src/xen/xen_driver.c

@@ -51,6 +51,7 @@
 #include "fdstream.h"
 #include "virfile.h"
 #include "command.h"
+#include "virnodesuspend.h"
 
 #define VIR_FROM_THIS VIR_FROM_XEN
 
@@ -2257,6 +2258,7 @@ static virDriver xenUnifiedDriver = {
     .domainEventDeregisterAny = xenUnifiedDomainEventDeregisterAny, /* 0.8.0 */
     .domainOpenConsole = xenUnifiedDomainOpenConsole, /* 0.8.6 */
     .isAlive = xenUnifiedIsAlive, /* 0.9.8 */
+    .nodeSuspendForDuration = nodeSuspendForDuration, /* 0.9.8 */
 };
 
 /**