genode/repos/os/include/cli_monitor/child.h
Norman Feske eaac3cc1bd Revised API documentation
This patch curates the API documentation to become suitable for the
functional specificaton, which is partially generated from the header
files.
2015-04-09 16:04:46 +02:00

314 lines
8.1 KiB
C++

/*
* \brief Child handling
* \author Norman Feske
* \date 2013-10-05
*/
/*
* Copyright (C) 2013 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__CLI_MONITOR__CHILD_H_
#define _INCLUDE__CLI_MONITOR__CHILD_H_
/* Genode includes */
#include <util/list.h>
#include <base/child.h>
#include <init/child_policy.h>
#include <os/child_policy_dynamic_rom.h>
#include <cpu_session/connection.h>
/* CLI-monitor includes */
#include <cli_monitor/ram.h>
class Child_base : public Genode::Child_policy
{
public:
/*
* XXX derive donated quota from information to be provided by
* the used 'Connection' interfaces
*/
enum { DONATED_RAM_QUOTA = 128*1024 };
class Quota_exceeded : public Genode::Exception { };
typedef Genode::String<128> Label;
typedef Genode::size_t size_t;
private:
Ram &_ram;
Label const _label;
struct Resources
{
Genode::Ram_connection ram;
Genode::Cpu_connection cpu;
Genode::Rm_connection rm;
Resources(const char *label, Genode::size_t ram_quota)
: ram(label), cpu(label)
{
if (ram_quota > DONATED_RAM_QUOTA)
ram_quota -= DONATED_RAM_QUOTA;
else
throw Quota_exceeded();
ram.ref_account(Genode::env()->ram_session_cap());
if (Genode::env()->ram_session()->transfer_quota(ram.cap(), ram_quota) != 0)
throw Quota_exceeded();
}
};
size_t _ram_quota;
size_t _ram_limit;
Resources _resources;
Genode::Service_registry _parent_services;
Genode::Rom_connection _binary_rom;
enum { ENTRYPOINT_STACK_SIZE = 12*1024 };
Genode::Rpc_entrypoint _entrypoint;
Init::Child_policy_enforce_labeling _labeling_policy;
Init::Child_policy_provide_rom_file _binary_policy;
Genode::Child_policy_dynamic_rom_file _config_policy;
Genode::Child _child;
/**
* If set to true, immediately withdraw resources yielded by the child
*/
bool _withdraw_on_yield_response = false;
/**
* Arguments of current resource request from the child
*/
Genode::Parent::Resource_args _resource_args;
Genode::Signal_context_capability _yield_response_sigh_cap;
public:
Child_base(Ram &ram,
char const *label,
char const *binary,
Genode::Cap_session &cap_session,
Genode::size_t ram_quota,
Genode::size_t ram_limit,
Genode::Signal_context_capability yield_response_sig_cap)
:
_ram(ram),
_label(label),
_ram_quota(ram_quota),
_ram_limit(ram_limit),
_resources(_label.string(), _ram_quota),
_binary_rom(binary, _label.string()),
_entrypoint(&cap_session, ENTRYPOINT_STACK_SIZE, _label.string(), false),
_labeling_policy(_label.string()),
_binary_policy("binary", _binary_rom.dataspace(), &_entrypoint),
_config_policy("config", _entrypoint, &_resources.ram),
_child(_binary_rom.dataspace(),
_resources.ram.cap(), _resources.cpu.cap(),
_resources.rm.cap(), &_entrypoint, this),
_yield_response_sigh_cap(yield_response_sig_cap)
{ }
Label label() const { return _label; }
void configure(char const *config, size_t config_len)
{
_config_policy.load(config, config_len);
}
void start()
{
_entrypoint.activate();
}
/**
* Issue yield request to the child
*/
void yield(size_t amount, bool greedy)
{
if (requested_ram_quota())
return; /* resource request in flight */
char buf[128];
Genode::snprintf(buf, sizeof(buf), "ram_quota=%zd", amount);
_withdraw_on_yield_response = greedy;
_child.yield(buf);
}
/**
* Return amount of RAM currently requested by the child
*/
size_t requested_ram_quota() const
{
return Genode::Arg_string::find_arg(_resource_args.string(), "ram_quota").ulong_value(0);
}
/**
* Withdraw quota from the child
*
* \throw Ram::Transfer_quota_failed
*/
void withdraw_ram_quota(size_t amount)
{
if (!amount)
return;
_ram.withdraw_from(_resources.ram.cap(), amount);
_ram_quota -= amount;
}
/**
* Upgrade quota of child
*
* \throw Ram::Transfer_quota_failed
*/
void upgrade_ram_quota(size_t amount)
{
_ram.transfer_to(_resources.ram.cap(), amount);
_ram_quota += amount;
/* wake up child if resource request is in flight */
size_t const req = requested_ram_quota();
if (req && _resources.ram.avail() >= req) {
_child.notify_resource_avail();
/* clear request state */
_resource_args = Genode::Parent::Resource_args("");
}
}
/**
* Try to respond to a current resource request issued by the child
*
* This method evaluates the conditions, under which a resource
* request can be answered: There must be enough room between the
* current quota and the configured limit, and there must be enough
* slack memory available. If both conditions are met, the quota
* of the child gets upgraded.
*/
void try_response_to_resource_request()
{
size_t const req = requested_ram_quota();
if (!req)
return; /* no resource request in flight */
/*
* Respond to the current request if the requested quota fits
* within the limit and if there is enough free quota available.
*/
if (req <= _ram.status().avail && req + _ram_quota <= _ram_limit) {
try { upgrade_ram_quota(req); }
catch (Ram::Transfer_quota_failed) { }
}
}
/**
* Set limit for on-demand RAM quota expansion
*/
void ram_limit(size_t limit)
{
_ram_limit = limit;
try_response_to_resource_request();
}
struct Ram_status
{
size_t quota = 0, limit = 0, xfer = 0, used = 0, avail = 0, req = 0;
Ram_status() { }
Ram_status(size_t quota, size_t limit, size_t xfer, size_t used,
size_t avail, size_t req)
:
quota(quota), limit(limit), xfer(xfer), used(used),
avail(avail), req(req)
{ }
};
/**
* Return RAM quota status of the child
*
* XXX should be a const method, but the 'Ram_session' accessors
* are not const
*/
Ram_status ram_status()
{
return Ram_status(_ram_quota,
_ram_limit,
_ram_quota - _resources.ram.quota(),
_resources.ram.used(),
_resources.ram.avail(),
requested_ram_quota());
}
/****************************
** Child_policy interface **
****************************/
const char *name() const { return _label.string(); }
Genode::Service *resolve_session_request(const char *service_name,
const char *args)
{
Genode::Service *service = 0;
/* check for binary file request */
if ((service = _binary_policy.resolve_session_request(service_name, args)))
return service;
/* check for config file request */
if ((service = _config_policy.resolve_session_request(service_name, args)))
return service;
/* fill parent service registry on demand */
if (!(service = _parent_services.find(service_name))) {
service = new (Genode::env()->heap())
Genode::Parent_service(service_name);
_parent_services.insert(service);
}
/* return parent service */
return service;
}
void filter_session_args(const char *service,
char *args, Genode::size_t args_len)
{
_labeling_policy.filter_session_args(service, args, args_len);
}
void yield_response()
{
if (_withdraw_on_yield_response) {
enum { RESERVE = 4*1024*1024 };
size_t amount = _resources.ram.avail() < RESERVE
? 0 : _resources.ram.avail() - RESERVE;
/* try to immediately withdraw freed-up resources */
try { withdraw_ram_quota(amount); }
catch (Ram::Transfer_quota_failed) { }
}
/* propagate yield-response signal */
Genode::Signal_transmitter(_yield_response_sigh_cap).submit();
}
void resource_request(Genode::Parent::Resource_args const &args)
{
_resource_args = args;
try_response_to_resource_request();
}
};
#endif /* _INCLUDE__CLI_MONITOR__CHILD_H_ */