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[#1733] kea-dhcp4 now implements Core Packet Parking

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Initial working implementation.

src/bin/dhcp4/dhcp4_srv.cc
    Dhcpv4Srv::processDhcp4Query() - reworked to
    proactively park the packet if lease4_commited callouts
    are installed.

src/lib/hooks/hooks_manager.h
    HooksManager::park() - added require_reference parameter

src/lib/hooks/parking_lots.h
    ParkingLot::park() - set refcount to zero, when added
    without pre-existing reference
This commit is contained in:
Thomas Markwalder
2021-04-01 16:38:43 -04:00
parent f2ffdb5b68
commit e63033adbe
3 changed files with 58 additions and 51 deletions
Download Patch File Download Diff File Expand all files Collapse all files

99
src/bin/dhcp4/dhcp4_srv.cc
View File

@@ -1317,11 +1317,8 @@ Dhcpv4Srv::processDhcp4Query(Pkt4Ptr& query, Pkt4Ptr& rsp,
static_cast<int64_t>(1));
}
bool packet_park = false;
CalloutHandlePtr callout_handle = getCalloutHandle(query);
if (ctx && HooksManager::calloutsPresent(Hooks.hook_index_leases4_committed_)) {
CalloutHandlePtr callout_handle = getCalloutHandle(query);
// Use the RAII wrapper to make sure that the callout handle state is
// reset when this object goes out of scope. All hook points must do
// it to prevent possible circular dependency between the callout
@@ -1348,55 +1345,61 @@ Dhcpv4Srv::processDhcp4Query(Pkt4Ptr& query, Pkt4Ptr& rsp,
}
callout_handle->setArgument("deleted_leases4", deleted_leases);
// Call all installed callouts
HooksManager::callCallouts(Hooks.hook_index_leases4_committed_,
*callout_handle);
if (allow_packet_park) {
// We proactively park the packet. We'll unpark it without invoking
// the callback (i.e. drop) unless the callout status is set to
// is NEXT_STEP_PARK. Otherwise the callback we bind here will be
// executed when the hook library unparks the packet.
HooksManager::park("leases4_committed", query,
[this, callout_handle, query, rsp]() mutable {
if (MultiThreadingMgr::instance().getMode()) {
typedef function<void()> CallBack;
boost::shared_ptr<CallBack> call_back =
boost::make_shared<CallBack>(std::bind(&Dhcpv4Srv::sendResponseNoThrow,
this, callout_handle, query, rsp));
MultiThreadingMgr::instance().getThreadPool().add(call_back);
} else {
processPacketPktSend(callout_handle, query, rsp);
processPacketBufferSend(callout_handle, rsp);
}
}, false);
}
if (callout_handle->getStatus() == CalloutHandle::NEXT_STEP_DROP) {
LOG_DEBUG(hooks_logger, DBG_DHCP4_HOOKS,
DHCP4_HOOK_LEASES4_COMMITTED_DROP)
.arg(query->getLabel());
try {
// Call all installed callouts
HooksManager::callCallouts(Hooks.hook_index_leases4_committed_,
*callout_handle);
} catch(...) {
// Make sure we don't orphan a parked packet.
if (allow_packet_park) {
HooksManager::drop("leases4_committed", query);
}
throw;
}
if ((callout_handle->getStatus() == CalloutHandle::NEXT_STEP_PARK)
&& allow_packet_park) {
LOG_DEBUG(hooks_logger, DBG_DHCP4_HOOKS, DHCP4_HOOK_LEASES4_COMMITTED_PARK)
.arg(query->getLabel());
// Since the hook library(ies) are going to do the unparking, then
// reset the pointer to the response to indicate to the caller that
// it should return, as the packet processing will continue via
// the callback.
rsp.reset();
} else if ((callout_handle->getStatus() == CalloutHandle::NEXT_STEP_PARK)
&& allow_packet_park) {
packet_park = true;
} else {
// Drop the park job on the packet, it isn't needed.
HooksManager::drop("leases4_committed", query);
if (callout_handle->getStatus() == CalloutHandle::NEXT_STEP_DROP) {
LOG_DEBUG(hooks_logger, DBG_DHCP4_HOOKS, DHCP4_HOOK_LEASES4_COMMITTED_DROP)
.arg(query->getLabel());
rsp.reset();
}
}
}
if (!rsp) {
return;
}
// PARKING SPOT after leases4_committed hook point.
CalloutHandlePtr callout_handle = getCalloutHandle(query);
if (packet_park) {
LOG_DEBUG(hooks_logger, DBG_DHCP4_HOOKS,
DHCP4_HOOK_LEASES4_COMMITTED_PARK)
.arg(query->getLabel());
// Park the packet. The function we bind here will be executed when the hook
// library unparks the packet.
HooksManager::park("leases4_committed", query,
[this, callout_handle, query, rsp]() mutable {
if (MultiThreadingMgr::instance().getMode()) {
typedef function<void()> CallBack;
boost::shared_ptr<CallBack> call_back =
boost::make_shared<CallBack>(std::bind(&Dhcpv4Srv::sendResponseNoThrow,
this, callout_handle, query, rsp));
MultiThreadingMgr::instance().getThreadPool().add(call_back);
} else {
processPacketPktSend(callout_handle, query, rsp);
processPacketBufferSend(callout_handle, rsp);
}
});
// If we have parked the packet, let's reset the pointer to the
// response to indicate to the caller that it should return, as
// the packet processing will continue via the callback.
rsp.reset();
} else {
// If we have a response prep it for shipment.
if (rsp) {
processPacketPktSend(callout_handle, query, rsp);
}
}

6
src/lib/hooks/hooks_manager.h
View File

@@ -289,9 +289,11 @@ public:
/// @param unpark_callback callback invoked when the packet is unparked.
template<typename T>
static void park(const std::string& hook_name, T parked_object,
std::function<void()> unpark_callback) {
std::function<void()> unpark_callback,
bool require_reference = true) {
ServerHooks::getServerHooks().
getParkingLotPtr(hook_name)->park(parked_object, unpark_callback);
getParkingLotPtr(hook_name)->park(parked_object, unpark_callback,
require_reference);
}
/// @brief Forces unparking the object (packet).

4
src/lib/hooks/parking_lots.h
View File

@@ -86,8 +86,10 @@ public:
" reference does not exist.");
}
// Not there add it.
// Not there add it. We reset the refcount to zero since
// techinically there are no references yet.
ParkingInfo pinfo(parked_object, unpark_callback);
pinfo.refcount_ = 0;
parking_[makeKey(parked_object)] = pinfo;
return;
}