Re: [libvirt] [PATCH] Introduce yet another migration version in API.

This patch attempts to introduce a version 3 that uses the improved 5 step sequence * Src: Begin - Generate XML to pass to dst - Generate optional cookie to pass to dst * Dst: Prepare - Get ready to accept incoming VM - Generate optional cookie to pass to src * Src: Perform - Start migration and wait for send completion - Generate optional cookie to pass to dst * Dst: Finish - Wait for recv completion and check status - Kill off VM if failed, resume if success - Generate optional cookie to pass to src * Src: Confirm - Kill off VM if success, resume if failed The API is designed to allow both input and output cookies in all methods where applicable. This lets us pass around arbitrary extra driver specific data between src & dst during migration. Combined with the extra 'Begin' method this lets us pass lease information from source to dst at the start of migration Moving the killing of the source VM out of Perform and into Confirm, means we can now recover if the dst host can't successfully Finish receiving migration data.

diff --git a/src/libvirt.c b/src/libvirt.c index e24fb9e..04a7cd0 100644 --- a/src/libvirt.c +++ b/src/libvirt.c

+/* + * Sequence v3: + * + * Src: Begin + * - Generate XML to pass to dst + * - Generate optional cookie to pass to dst + * + * Dst: Prepare + * - Get ready to accept incoming VM + * - Generate optional cookie to pass to src + * + * Src: Perform + * - Start migration and wait for send completion + * - Generate optional cookie to pass to dst + * + * Dst: Finish + * - Wait for recv completion and check status + * - Kill off VM if failed, resume if success + * - Generate optional cookie to pass to src + * + * Src: Confirm + * - Kill off VM if success, resume if failed + * + */ +static virDomainPtr +virDomainMigrateVersion3 (virDomainPtr domain, + virConnectPtr dconn, + unsigned long flags, + const char *dname, + const char *uri, + unsigned long bandwidth) +{ + virDomainPtr ddomain = NULL; + char *uri_out = NULL; + char *cookiesrc = NULL; + char *cookiedst = NULL; + char *dom_xml = NULL; + int cookiesrclen = 0; + int cookiedstlen = 0; + int ret; + virDomainInfo info; + virErrorPtr orig_err = NULL; + + if (!domain->conn->driver->domainMigrateBegin3) { + virLibConnError (domain->conn, VIR_ERR_INTERNAL_ERROR, __FUNCTION__); + virDispatchError(domain->conn); + return NULL; + } + dom_xml = domain->conn->driver->domainMigrateBegin3 + (domain->conn, &cookiesrc, &cookiesrclen, uri, flags, dname, + bandwidth); + if (!dom_xml) + goto done; + + ret = virDomainGetInfo (domain, &info); + if (ret == 0 && info.state == VIR_DOMAIN_PAUSED) { + flags |= VIR_MIGRATE_PAUSED; + } + + ret = dconn->driver->domainMigratePrepare3 + (dconn, cookiesrc, cookiesrclen, &cookiedst, &cookiedstlen, + uri, &uri_out, flags, dname, bandwidth, dom_xml); + VIR_FREE (dom_xml); + if (ret == -1) + goto done; + + if (uri == NULL && uri_out == NULL) { + virLibConnError (domain->conn, VIR_ERR_INTERNAL_ERROR, + _("domainMigratePrepare2 did not set uri")); + virDispatchError(domain->conn); + goto done; + } + if (uri_out) + uri = uri_out; /* Did domainMigratePrepare2 change URI? */ + assert (uri != NULL);