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plugin_hook: special case for db hook.

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I started by trying to change the current infrastructure, but this is
really the only completely sync hook which makes sense; it needs to avoid
doing the db_transation, as well as waiting, and using a callback is just
overkill.

So with some regret, I open coded it.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2019-03-18 13:10:32 +10:30
parent 3729ad9914
commit 4ca2964d21
2 changed files with 76 additions and 0 deletions
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72
lightningd/plugin_hook.c
View file

@ -1,3 +1,4 @@
#include <ccan/io/io.h>
#include <common/memleak.h>
#include <lightningd/jsonrpc.h>
#include <lightningd/plugin_hook.h>
@ -89,3 +90,74 @@ void plugin_hook_call_(struct lightningd *ld, const struct plugin_hook *hook,
hook->response_cb(cb_arg, NULL);
}
}
/* We open-code this, because it's just different and special enough to be
* annoying, and to make it clear that it's totally synchronous. */
/* Special synchronous hook for db */
static struct plugin_hook db_write_hook = { "db_write", NULL, NULL, NULL, NULL };
AUTODATA(hooks, &db_write_hook);
static void db_hook_response(const char *buffer, const jsmntok_t *toks,
const jsmntok_t *idtok,
struct plugin_hook_request *ph_req)
{
const jsmntok_t *resulttok;
bool resp;
resulttok = json_get_member(buffer, toks, "result");
if (!resulttok)
fatal("Plugin returned an invalid response to the db_write "
"hook: %s", buffer);
/* We expect result: True. Anything else we abort. */
if (!json_to_bool(buffer, resulttok, &resp))
fatal("Plugin returned an invalid result to the db_write "
"hook: %s", buffer);
/* If it fails, we must not commit to our db. */
if (!resp)
fatal("Plugin returned failed db_write: %s.", buffer);
/* We're done, exit exclusive loop. */
io_break(ph_req);
}
void plugin_hook_db_sync(struct db *db, const char **changes, const char *final)
{
const struct plugin_hook *hook = &db_write_hook;
struct jsonrpc_request *req;
struct plugin_hook_request *ph_req;
void *ret;
if (!hook->plugin)
return;
ph_req = notleak(tal(hook->plugin, struct plugin_hook_request));
/* FIXME: do IO logging for this! */
req = jsonrpc_request_start(NULL, hook->name, NULL, db_hook_response,
ph_req);
ph_req->hook = hook;
ph_req->db = db;
json_array_start(req->stream, "writes");
for (size_t i = 0; i < tal_count(changes); i++)
json_add_string(req->stream, NULL, changes[i]);
if (final)
json_add_string(req->stream, NULL, final);
json_array_end(req->stream);
jsonrpc_request_end(req);
plugin_request_send(hook->plugin, req);
/* We can be called on way out of an io_loop, which is already breaking.
* That will make this immediately return; save the break value and call
* again, then hand it onwards. */
ret = plugin_exclusive_loop(hook->plugin);
if (ret != ph_req) {
void *ret2 = plugin_exclusive_loop(hook->plugin);
assert(ret2 == ph_req);
io_break(ret);
}
}

4
lightningd/plugin_hook.h
View file

@ -112,4 +112,8 @@ void plugin_hook_call_(struct lightningd *ld, const struct plugin_hook *hook,
bool plugin_hook_register(struct plugin *plugin, const char *method);
/* Special sync plugin hook for db: changes[] are SQL statements, with optional
* final command appended. */
void plugin_hook_db_sync(struct db *db, const char **changes, const char *final);
#endif /* LIGHTNING_LIGHTNINGD_PLUGIN_HOOK_H */