Simplified distributed block storage with strong consistency, like in Ceph
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// Copyright (c) Vitaliy Filippov, 2019+
// License: VNPL-1.0 or GNU GPL-2.0+ (see README.md for details)
// C-C++ proxy for the QEMU driver
// (QEMU headers don't compile with g++)
#include <sys/epoll.h>
#include "cluster_client.h"
typedef void* AioContext;
#include "qemu_proxy.h"
extern "C"
{
// QEMU
typedef void IOHandler(void *opaque);
void aio_set_fd_handler(AioContext *ctx, int fd, int is_external, IOHandler *fd_read, IOHandler *fd_write, void *poll_fn, void *opaque);
}
struct QemuProxyData
{
int fd;
std::function<void(int, int)> callback;
};
class QemuProxy
{
std::map<int, QemuProxyData> handlers;
public:
timerfd_manager_t *tfd;
cluster_client_t *cli;
AioContext *ctx;
QemuProxy(AioContext *ctx, const char *etcd_host, const char *etcd_prefix)
{
this->ctx = ctx;
json11::Json cfg = json11::Json::object {
{ "etcd_address", std::string(etcd_host) },
{ "etcd_prefix", std::string(etcd_prefix ? etcd_prefix : "/vitastor") },
};
tfd = new timerfd_manager_t([this](int fd, bool wr, std::function<void(int, int)> callback) { set_fd_handler(fd, wr, callback); });
cli = new cluster_client_t(NULL, tfd, cfg);
}
~QemuProxy()
{
cli->stop();
delete cli;
delete tfd;
}
void set_fd_handler(int fd, bool wr, std::function<void(int, int)> callback)
{
if (callback != NULL)
{
handlers[fd] = { .fd = fd, .callback = callback };
aio_set_fd_handler(ctx, fd, false, &QemuProxy::read_handler, wr ? &QemuProxy::write_handler : NULL, NULL, &handlers[fd]);
}
else
{
handlers.erase(fd);
aio_set_fd_handler(ctx, fd, false, NULL, NULL, NULL, NULL);
}
}
static void read_handler(void *opaque)
{
QemuProxyData *data = (QemuProxyData *)opaque;
data->callback(data->fd, EPOLLIN);
}
static void write_handler(void *opaque)
{
QemuProxyData *data = (QemuProxyData *)opaque;
data->callback(data->fd, EPOLLOUT);
}
};
extern "C" {
void* vitastor_proxy_create(AioContext *ctx, const char *etcd_host, const char *etcd_prefix)
{
QemuProxy *p = new QemuProxy(ctx, etcd_host, etcd_prefix);
return p;
}
void vitastor_proxy_destroy(void *client)
{
QemuProxy *p = (QemuProxy*)client;
delete p;
}
void vitastor_proxy_rw(int write, void *client, uint64_t inode, uint64_t offset, uint64_t len,
iovec *iov, int iovcnt, VitastorIOHandler cb, void *opaque)
{
QemuProxy *p = (QemuProxy*)client;
cluster_op_t *op = new cluster_op_t;
op->opcode = write ? OSD_OP_WRITE : OSD_OP_READ;
op->inode = inode;
op->offset = offset;
op->len = len;
for (int i = 0; i < iovcnt; i++)
{
op->iov.push_back(iov[i].iov_base, iov[i].iov_len);
}
op->callback = [cb, opaque](cluster_op_t *op)
{
cb(op->retval, opaque);
delete op;
};
p->cli->execute(op);
}
void vitastor_proxy_sync(void *client, VitastorIOHandler cb, void *opaque)
{
QemuProxy *p = (QemuProxy*)client;
cluster_op_t *op = new cluster_op_t;
op->opcode = OSD_OP_SYNC;
op->callback = [cb, opaque](cluster_op_t *op)
{
cb(op->retval, opaque);
delete op;
};
p->cli->execute(op);
}
}