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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
#pragma once
#include "osd_types.h"
struct ObjectState {
object_info_t oi;
bool exists; ///< the stored object exists (i.e., we will remember the object_info_t)
ObjectState() : exists(false) {}
ObjectState(const object_info_t &oi_, bool exists_)
: oi(oi_), exists(exists_) {}
ObjectState(object_info_t &&oi_, bool exists_)
: oi(std::move(oi_)), exists(exists_) {}
ObjectState(const hobject_t &obj) : oi(obj), exists(false) {}
};
struct RWState {
enum State {
RWNONE,
RWREAD,
RWWRITE,
RWEXCL,
};
static const char *get_state_name(State s) {
switch (s) {
case RWNONE: return "none";
case RWREAD: return "read";
case RWWRITE: return "write";
case RWEXCL: return "excl";
default: return "???";
}
}
const char *get_state_name() const {
return get_state_name(state);
}
int count; ///< number of readers or writers
int waiters = 0; ///< number waiting
State state:4; ///< rw state
/// if set, restart backfill when we can get a read lock
bool recovery_read_marker:1;
/// if set, requeue snaptrim on lock release
bool snaptrimmer_write_marker:1;
RWState()
: count(0),
state(RWNONE),
recovery_read_marker(false),
snaptrimmer_write_marker(false)
{}
/// this function adjusts the counts if necessary
bool get_read_lock() {
// don't starve anybody!
if (waiters > 0) {
return false;
}
switch (state) {
case RWNONE:
ceph_assert(count == 0);
state = RWREAD;
// fall through
case RWREAD:
count++;
return true;
case RWWRITE:
return false;
case RWEXCL:
return false;
default:
ceph_abort_msg("unhandled case");
return false;
}
}
bool get_write_lock(bool greedy=false) {
if (!greedy) {
// don't starve anybody!
if (waiters > 0 ||
recovery_read_marker) {
return false;
}
}
switch (state) {
case RWNONE:
ceph_assert(count == 0);
state = RWWRITE;
// fall through
case RWWRITE:
count++;
return true;
case RWREAD:
return false;
case RWEXCL:
return false;
default:
ceph_abort_msg("unhandled case");
return false;
}
}
bool get_excl_lock() {
switch (state) {
case RWNONE:
ceph_assert(count == 0);
state = RWEXCL;
count = 1;
return true;
case RWWRITE:
return false;
case RWREAD:
return false;
case RWEXCL:
return false;
default:
ceph_abort_msg("unhandled case");
return false;
}
}
/// same as get_write_lock, but ignore starvation
bool take_write_lock() {
if (state == RWWRITE) {
count++;
return true;
}
return get_write_lock();
}
bool dec() {
ceph_assert(count > 0);
count--;
if (count == 0) {
state = RWNONE;
return true;
} else {
return false;
}
}
bool put_read() {
ceph_assert(state == RWREAD);
return dec();
}
bool put_write() {
ceph_assert(state == RWWRITE);
return dec();
}
bool put_excl() {
ceph_assert(state == RWEXCL);
return dec();
}
void inc_waiters() {
++waiters;
}
void release_waiters() {
waiters = 0;
}
void dec_waiters(int count) {
ceph_assert(waiters >= count);
waiters -= count;
}
bool empty() const { return state == RWNONE; }
bool get_snaptrimmer_write(bool mark_if_unsuccessful) {
if (get_write_lock()) {
return true;
} else {
if (mark_if_unsuccessful)
snaptrimmer_write_marker = true;
return false;
}
}
bool get_recovery_read() {
recovery_read_marker = true;
if (get_read_lock()) {
return true;
}
return false;
}
};
inline std::ostream& operator<<(std::ostream& out, const RWState& rw)
{
return out << "rwstate(" << rw.get_state_name()
<< " n=" << rw.count
<< " w=" << rw.waiters
<< ")";
}
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