mirror of
https://github.com/genodelabs/genode.git
synced 2025-02-22 02:16:44 +00:00
block_session: new client-side API
This patch equips the 'Block::Connection' with a framework API for the implementation of robust block-session clients that perform block I/O in an asynchronous fashion. An application-defined 'JOB' type, inherited from 'Connection::Job', encapsulates the application's context information associated with a block operation. The lifecycle of the jobs is implemented by the 'Connection' and driven by the application's invokation of 'Connection::update_jobs'. The 'update_jobs' mechanism takes three hook functions as arguments, which implement the applications-defined policy for producing and consuming data, and for the completion of jobs. Issue #3283
This commit is contained in:
Norman Feske
Christian Helmuth
parent
976f67eee6
commit
784206c85c
@ -43,6 +43,11 @@ struct Block::Operation
|
||||
|| type == Type::SYNC || type == Type::TRIM;
|
||||
}
|
||||
|
||||
static bool has_payload(Type type)
|
||||
{
|
||||
return type == Type::READ || type == Type::WRITE;
|
||||
}
|
||||
|
||||
static char const *type_name(Type type)
|
||||
{
|
||||
switch (type) {
|
||||
|
||||
@ -23,7 +23,7 @@ namespace Block { class Session_client; }
|
||||
|
||||
class Block::Session_client : public Genode::Rpc_client<Session>
|
||||
{
|
||||
private:
|
||||
protected:
|
||||
|
||||
Packet_stream_tx::Client<Tx> _tx;
|
||||
|
||||
|
||||
@ -1,11 +1,11 @@
|
||||
/*
|
||||
* \brief Connection to block service
|
||||
* \author Stefan Kalkowski
|
||||
* \date 2010-07-07
|
||||
* \author Norman Feske
|
||||
* \date 2019-04-10
|
||||
*/
|
||||
|
||||
/*
|
||||
* Copyright (C) 2010-2017 Genode Labs GmbH
|
||||
* Copyright (C) 2019 Genode Labs GmbH
|
||||
*
|
||||
* This file is part of the Genode OS framework, which is distributed
|
||||
* under the terms of the GNU Affero General Public License version 3.
|
||||
@ -17,6 +17,8 @@
|
||||
#include <block_session/client.h>
|
||||
#include <base/connection.h>
|
||||
#include <base/allocator.h>
|
||||
#include <base/id_space.h>
|
||||
#include <util/fifo.h>
|
||||
|
||||
namespace Block { template <typename> struct Connection; }
|
||||
|
||||
@ -24,24 +26,437 @@ namespace Block { template <typename> struct Connection; }
|
||||
template <typename JOB = void>
|
||||
struct Block::Connection : Genode::Connection<Session>, Session_client
|
||||
{
|
||||
/**
|
||||
* Constructor
|
||||
*
|
||||
* \param tx_buffer_alloc allocator used for managing the
|
||||
* transmission buffer
|
||||
* \param tx_buf_size size of transmission buffer in bytes
|
||||
*/
|
||||
Connection(Genode::Env &env,
|
||||
Genode::Range_allocator *tx_block_alloc,
|
||||
Genode::size_t tx_buf_size = 128*1024,
|
||||
const char *label = "")
|
||||
:
|
||||
Genode::Connection<Session>(env,
|
||||
session(env.parent(),
|
||||
"ram_quota=%ld, cap_quota=%ld, tx_buf_size=%ld, label=\"%s\"",
|
||||
14*1024 + tx_buf_size, CAP_QUOTA, tx_buf_size, label)),
|
||||
Session_client(cap(), *tx_block_alloc, env.rm())
|
||||
{ }
|
||||
public:
|
||||
|
||||
class Job;
|
||||
|
||||
typedef Genode::size_t size_t;
|
||||
|
||||
private:
|
||||
|
||||
/*
|
||||
* Define internally used '_JOB' type that corresponds to the 'JOB'
|
||||
* template argument but falls back to 'Job' if no template argument
|
||||
* is given.
|
||||
*/
|
||||
template <typename T, typename> struct Fallback { typedef T Type; };
|
||||
template <typename FB> struct Fallback<void, FB> { typedef FB Type; };
|
||||
|
||||
typedef typename Fallback<JOB, Job>::Type _JOB;
|
||||
|
||||
typedef Genode::Id_space<_JOB> Tag_id_space;
|
||||
|
||||
typedef Packet_descriptor::Payload Payload;
|
||||
|
||||
public:
|
||||
|
||||
class Job : Genode::Noncopyable
|
||||
{
|
||||
private:
|
||||
|
||||
friend class Connection;
|
||||
|
||||
Connection &_connection;
|
||||
|
||||
Operation const _operation;
|
||||
|
||||
/*
|
||||
* Block offset relative to '_operation.block_number', used
|
||||
* when performing large read/write operations in multiple
|
||||
* steps.
|
||||
*/
|
||||
block_count_t _position = 0;
|
||||
|
||||
/*
|
||||
* Packet-stream allocation used for read/write operations
|
||||
*/
|
||||
Payload _payload { };
|
||||
|
||||
bool _completed = false;
|
||||
|
||||
/*
|
||||
* A job undergoes three stages. The transition from one
|
||||
* stage to the next happens 'update_jobs'.
|
||||
*
|
||||
* Initially, it resides in the '_pending' fifo queue.
|
||||
*
|
||||
* Once submitted, it is removed from the '_pending' fifo
|
||||
* and added to the '_tags' ID space.
|
||||
*
|
||||
* Once acknowledged and complete, it is removed from the
|
||||
* '_tags' ID space.
|
||||
*/
|
||||
|
||||
Genode::Constructible<typename Tag_id_space::Element> _tag { };
|
||||
|
||||
Genode::Fifo_element<_JOB> _pending_elem {
|
||||
*static_cast<_JOB *>(this) };
|
||||
|
||||
Operation _curr_operation() const
|
||||
{
|
||||
if (!Operation::has_payload(_operation.type))
|
||||
return _operation;
|
||||
|
||||
return {
|
||||
.type = _operation.type,
|
||||
.block_number = _operation.block_number + _position,
|
||||
.count = Genode::min(_connection._max_block_count,
|
||||
_operation.count - _position) };
|
||||
}
|
||||
|
||||
template <typename FN>
|
||||
static void _with_offset_and_length(Job &job, FN const &fn)
|
||||
{
|
||||
if (!Operation::has_payload(job._operation.type))
|
||||
return;
|
||||
|
||||
Operation const operation = job._curr_operation();
|
||||
size_t const block_size = job._connection._info.block_size;
|
||||
|
||||
fn(operation.block_number * block_size,
|
||||
Genode::min(job._payload.bytes, operation.count * block_size));
|
||||
}
|
||||
|
||||
template <typename POLICY>
|
||||
void _submit(POLICY &policy, _JOB &job, Tx::Source &tx)
|
||||
{
|
||||
if (!_tag.constructed())
|
||||
return;
|
||||
|
||||
Request::Tag const tag { _tag->id().value };
|
||||
|
||||
Packet_descriptor const p(_curr_operation(), _payload, tag);
|
||||
|
||||
if (_operation.type == Operation::Type::WRITE)
|
||||
_with_offset_and_length(job, [&] (off_t offset, size_t length) {
|
||||
policy.produce_write_content(job, offset,
|
||||
tx.packet_content(p),
|
||||
length); });
|
||||
tx.try_submit_packet(p);
|
||||
}
|
||||
|
||||
public:
|
||||
|
||||
Job(Connection &connection, Operation operation)
|
||||
:
|
||||
_connection(connection), _operation(operation)
|
||||
{
|
||||
_connection._pending.enqueue(_pending_elem);
|
||||
}
|
||||
|
||||
~Job()
|
||||
{
|
||||
if (pending()) {
|
||||
_connection._pending.remove(_pending_elem);
|
||||
}
|
||||
else if (in_progress()) {
|
||||
Genode::warning("block-session job prematurely destructed");
|
||||
}
|
||||
}
|
||||
|
||||
bool in_progress() const { return _tag.constructed(); }
|
||||
bool completed() const { return _completed; }
|
||||
bool pending() const { return !in_progress() && !completed(); }
|
||||
|
||||
Operation operation() const { return _operation; }
|
||||
};
|
||||
|
||||
private:
|
||||
|
||||
block_count_t const _max_block_count;
|
||||
|
||||
block_count_t _init_max_block_count(size_t buf_size) const
|
||||
{
|
||||
/*
|
||||
* Number of bytes that may be unusable at the beginning or
|
||||
* and of the buffer because of alignment constraints.
|
||||
*/
|
||||
size_t const align_scrap = 2*(1UL << _info.align_log2);
|
||||
|
||||
if (buf_size < align_scrap)
|
||||
return 0;
|
||||
|
||||
buf_size -= align_scrap;
|
||||
|
||||
return buf_size / _info.block_size;
|
||||
}
|
||||
|
||||
/**
|
||||
* Tag ID space of submitted jobs
|
||||
*/
|
||||
Tag_id_space _tags { };
|
||||
|
||||
/**
|
||||
* Jobs that are pending for submission
|
||||
*/
|
||||
Genode::Fifo<Genode::Fifo_element<_JOB>> _pending { };
|
||||
|
||||
/**
|
||||
* Process a single acknowledgement
|
||||
*
|
||||
* \return true if progress was made
|
||||
*/
|
||||
template <typename POLICY>
|
||||
bool _try_process_ack(POLICY &, Tx::Source &);
|
||||
|
||||
/**
|
||||
* Submit next pending job to server, if possible
|
||||
*
|
||||
* \return true if a job was successfully submitted
|
||||
*/
|
||||
template <typename POLICY>
|
||||
bool _try_submit_pending_job(POLICY &, Tx::Source &);
|
||||
|
||||
public:
|
||||
|
||||
/**
|
||||
* Constructor
|
||||
*
|
||||
* \param tx_buffer_alloc allocator used for managing the
|
||||
* transmission buffer
|
||||
* \param tx_buf_size size of transmission buffer in bytes
|
||||
*/
|
||||
Connection(Genode::Env &env,
|
||||
Genode::Range_allocator *tx_block_alloc,
|
||||
Genode::size_t tx_buf_size = 128*1024,
|
||||
const char *label = "")
|
||||
:
|
||||
Genode::Connection<Session>(env,
|
||||
session(env.parent(),
|
||||
"ram_quota=%ld, cap_quota=%ld, tx_buf_size=%ld, label=\"%s\"",
|
||||
14*1024 + tx_buf_size, CAP_QUOTA, tx_buf_size, label)),
|
||||
Session_client(cap(), *tx_block_alloc, env.rm()),
|
||||
_max_block_count(_init_max_block_count(_tx.source()->bulk_buffer_size()))
|
||||
{ }
|
||||
|
||||
/**
|
||||
* Register handler for data-flow signals
|
||||
*
|
||||
* The handler is triggered on the arrival of new acknowledgements or
|
||||
* when the server becomes ready for new requests. It is thereby able
|
||||
* to execute 'update_jobs' on these conditions.
|
||||
*/
|
||||
void sigh(Genode::Signal_context_capability sigh)
|
||||
{
|
||||
tx_channel()->sigh_ack_avail(sigh);
|
||||
tx_channel()->sigh_ready_to_submit(sigh);
|
||||
}
|
||||
|
||||
/**
|
||||
* Handle the submission and completion of block-operation jobs
|
||||
*
|
||||
* \return true if progress was made
|
||||
*/
|
||||
template <typename POLICY>
|
||||
bool update_jobs(POLICY &policy)
|
||||
{
|
||||
Tx::Source &tx = *_tx.source();
|
||||
|
||||
bool overall_progress = false;
|
||||
|
||||
for (;;) {
|
||||
|
||||
/* track progress of a single iteration */
|
||||
bool progress = false;
|
||||
|
||||
/* process acknowledgements */
|
||||
while (_try_process_ack(policy, tx))
|
||||
progress = true;
|
||||
|
||||
/* try to submit pending requests */
|
||||
while (_try_submit_pending_job(policy, tx))
|
||||
progress = true;
|
||||
|
||||
overall_progress |= progress;
|
||||
|
||||
if (!progress)
|
||||
break;
|
||||
}
|
||||
|
||||
if (overall_progress)
|
||||
tx.wakeup();
|
||||
|
||||
return overall_progress;
|
||||
}
|
||||
|
||||
/**
|
||||
* Interface of 'POLICY' argument for 'update_jobs'
|
||||
*/
|
||||
struct Update_jobs_policy
|
||||
{
|
||||
/**
|
||||
* Produce content for write operation
|
||||
*
|
||||
* \param offset position of to-be-written data window in bytes
|
||||
* \param dst destination buffer (located within the I/O
|
||||
* communication buffer shared with the server)
|
||||
* \param length size of 'dst' buffer in bytes
|
||||
*/
|
||||
void produce_write_content(Job &, off_t offset,
|
||||
char *dst, size_t length);
|
||||
|
||||
/**
|
||||
* Consume data resulting from read operation
|
||||
*
|
||||
* \param offset position of received data window in bytes
|
||||
* \param src pointer to received data
|
||||
* \param length number of bytes received
|
||||
*/
|
||||
void consume_read_result(Job &, off_t offset,
|
||||
char const *src, size_t length);
|
||||
|
||||
/**
|
||||
* Respond on the completion of the given job
|
||||
*/
|
||||
void completed(Job &, bool success);
|
||||
};
|
||||
|
||||
/**
|
||||
* Call 'fn' with each job as argument
|
||||
*
|
||||
* This method is intended for the destruction of the jobs associated
|
||||
* with the connection before destructing the 'Connection' object.
|
||||
*/
|
||||
template <typename FN>
|
||||
void dissolve_all_jobs(FN const &fn)
|
||||
{
|
||||
_pending.dequeue_all([&] (Genode::Fifo_element<_JOB> &elem) {
|
||||
fn(elem.object()); });
|
||||
|
||||
auto discard_tag_and_apply_fn = [&] (_JOB &job)
|
||||
{
|
||||
Job &job_base = job;
|
||||
job_base._tag.destruct();
|
||||
fn(job);
|
||||
};
|
||||
|
||||
while (_tags.template apply_any<_JOB>(discard_tag_and_apply_fn));
|
||||
}
|
||||
};
|
||||
|
||||
|
||||
template <typename JOB>
|
||||
template <typename POLICY>
|
||||
bool Block::Connection<JOB>::_try_process_ack(POLICY &policy, Tx::Source &tx)
|
||||
{
|
||||
/*
|
||||
* Tx must be ready to accept at least one submission.
|
||||
* This is needed to continue split read/write operations.
|
||||
*/
|
||||
if (!tx.ack_avail() || !tx.ready_to_submit())
|
||||
return false;
|
||||
|
||||
Packet_descriptor const p = tx.try_get_acked_packet();
|
||||
|
||||
Operation::Type const type = p.operation_type();
|
||||
|
||||
bool release_packet = true;
|
||||
|
||||
typename Tag_id_space::Id const id { p.tag().value };
|
||||
|
||||
try {
|
||||
_tags.template apply<_JOB>(id, [&] (_JOB &job) {
|
||||
|
||||
if (type == Operation::Type::READ)
|
||||
Job::_with_offset_and_length(job, [&] (off_t offset, size_t length) {
|
||||
policy.consume_read_result(job, offset,
|
||||
tx.packet_content(p), length); });
|
||||
|
||||
/* needed to access private members of 'Job' (friend) */
|
||||
Job &job_base = job;
|
||||
|
||||
bool const partial_read_or_write =
|
||||
p.succeeded() &&
|
||||
Operation::has_payload(type) &&
|
||||
(job_base._position + p.block_count() < job_base._operation.count);
|
||||
|
||||
if (partial_read_or_write) {
|
||||
|
||||
/*
|
||||
* Issue next part of split read/write operation while reusing the
|
||||
* existing payload allocation within the packet stream.
|
||||
*/
|
||||
job_base._position += p.block_count();
|
||||
job_base._submit(policy, job, tx);
|
||||
|
||||
release_packet = false;
|
||||
|
||||
} else {
|
||||
|
||||
job_base._completed = true;
|
||||
job_base._tag.destruct();
|
||||
|
||||
policy.completed(job, p.succeeded());
|
||||
}
|
||||
});
|
||||
}
|
||||
catch (typename Tag_id_space::Unknown_id) {
|
||||
Genode::warning("spurious block-operation acknowledgement");
|
||||
}
|
||||
|
||||
if (release_packet)
|
||||
tx.release_packet(p);
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
|
||||
template <typename JOB>
|
||||
template <typename POLICY>
|
||||
bool Block::Connection<JOB>::_try_submit_pending_job(POLICY &policy, Tx::Source &tx)
|
||||
{
|
||||
if (_pending.empty())
|
||||
return false;
|
||||
|
||||
/*
|
||||
* Preserve one slot for the submission, plus another slot to satisfy the
|
||||
* precondition of '_try_process_ack'.
|
||||
*/
|
||||
if (!tx.ready_to_submit(2))
|
||||
return false;
|
||||
|
||||
/*
|
||||
* Allocate space for the payload in the packet-stream buffer.
|
||||
*/
|
||||
|
||||
Payload payload { };
|
||||
try {
|
||||
_pending.head([&] (Genode::Fifo_element<_JOB> const &elem) {
|
||||
|
||||
Job const &job = elem.object();
|
||||
|
||||
if (!Operation::has_payload(job._operation.type))
|
||||
return;
|
||||
|
||||
size_t const bytes = _info.block_size * job._curr_operation().count;
|
||||
|
||||
payload = { .offset = tx.alloc_packet(bytes, _info.align_log2).offset(),
|
||||
.bytes = bytes };
|
||||
});
|
||||
}
|
||||
catch (Tx::Source::Packet_alloc_failed) {
|
||||
|
||||
/* the packet-stream buffer is saturated */
|
||||
return false;
|
||||
}
|
||||
|
||||
/*
|
||||
* All preconditions for the submission of the job are satisfied.
|
||||
* So the job can go from the pending to the in-progress stage.
|
||||
*/
|
||||
|
||||
_pending.dequeue([&] (Genode::Fifo_element<_JOB> &elem) {
|
||||
|
||||
Job &job = elem.object();
|
||||
|
||||
/* let the job join the tag ID space, allocating a tag */
|
||||
job._tag.construct(elem.object(), _tags);
|
||||
|
||||
job._payload = payload;
|
||||
job._submit(policy, elem.object(), tx);
|
||||
});
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
#endif /* _INCLUDE__BLOCK_SESSION__CONNECTION_H_ */
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user