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datastore: add generation, simple atomicity.

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We add a generation counter, and allow update or del conditional
on a given generation.

Formalizes error codes, too, since we have more now.

Suggested-by: @shesek
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2021-08-25 12:21:04 +09:30
committed by Christian Decker
parent 432508e65e
commit 533571a655
18 changed files with 241 additions and 117 deletions
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60
lightningd/datastore.c
View File

@@ -5,10 +5,12 @@
#include <wallet/wallet.h>
static void json_add_datastore(struct json_stream *response,
const char *key, const u8 *data)
const char *key, const u8 *data,
u64 generation)
{
const char *str;
json_add_string(response, "key", key);
json_add_u64(response, "generation", generation);
json_add_hex(response, "hex", data, tal_bytelen(data));
str = utf8_str(response, data, tal_bytelen(data));
if (str)
@@ -58,12 +60,14 @@ static struct command_result *json_datastore(struct command *cmd,
const char *key, *strdata;
u8 *data, *prevdata;
enum ds_mode *mode;
u64 *generation, actual_gen;
if (!param(cmd, buffer, params,
p_req("key", param_string, &key),
p_opt("string", param_string, &strdata),
p_opt("hex", param_bin_from_hex, &data),
p_opt_def("mode", param_mode, &mode, DS_MUST_NOT_EXIST),
p_opt("generation", param_u64, &generation),
NULL))
return command_param_failed();
@@ -78,15 +82,25 @@ static struct command_result *json_datastore(struct command *cmd,
"Must have either hex or string");
}
prevdata = wallet_datastore_fetch(cmd, cmd->ld->wallet, key);
if ((*mode & DS_MUST_NOT_EXIST) && prevdata)
if (generation && !(*mode & DS_MUST_EXIST))
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
"generation only valid with must-replace"
" or must-append");
prevdata = wallet_datastore_fetch(cmd, cmd->ld->wallet, key,
&actual_gen);
if ((*mode & DS_MUST_NOT_EXIST) && prevdata)
return command_fail(cmd, DATASTORE_UPDATE_ALREADY_EXISTS,
"Key already exists");
if ((*mode & DS_MUST_EXIST) && !prevdata)
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
return command_fail(cmd, DATASTORE_UPDATE_DOES_NOT_EXIST,
"Key does not exist");
if (generation && actual_gen != *generation)
return command_fail(cmd, DATASTORE_UPDATE_WRONG_GENERATION,
"generation is different");
if ((*mode & DS_APPEND) && prevdata) {
size_t prevlen = tal_bytelen(prevdata);
tal_resize(&prevdata, prevlen + tal_bytelen(data));
@@ -94,13 +108,16 @@ static struct command_result *json_datastore(struct command *cmd,
data = prevdata;
}
if (prevdata)
if (prevdata) {
wallet_datastore_update(cmd->ld->wallet, key, data);
else
actual_gen++;
} else {
wallet_datastore_create(cmd->ld->wallet, key, data);
actual_gen = 0;
}
response = json_stream_success(cmd);
json_add_datastore(response, key, data);
json_add_datastore(response, key, data, actual_gen);
return command_success(cmd, response);
}
@@ -112,6 +129,7 @@ static struct command_result *json_listdatastore(struct command *cmd,
struct json_stream *response;
const char *key;
const u8 *data;
u64 generation;
if (!param(cmd, buffer, params,
p_opt("key", param_string, &key),
@@ -121,22 +139,24 @@ static struct command_result *json_listdatastore(struct command *cmd,
response = json_stream_success(cmd);
json_array_start(response, "datastore");
if (key) {
data = wallet_datastore_fetch(cmd, cmd->ld->wallet, key);
data = wallet_datastore_fetch(cmd, cmd->ld->wallet, key,
&generation);
if (data) {
json_object_start(response, NULL);
json_add_datastore(response, key, data);
json_add_datastore(response, key, data, generation);
json_object_end(response);
}
} else {
struct db_stmt *stmt;
for (stmt = wallet_datastore_first(cmd, cmd->ld->wallet,
&key, &data);
&key, &data, &generation);
stmt;
stmt = wallet_datastore_next(cmd, cmd->ld->wallet,
stmt, &key, &data)) {
stmt, &key, &data,
&generation)) {
json_object_start(response, NULL);
json_add_datastore(response, key, data);
json_add_datastore(response, key, data, generation);
json_object_end(response);
}
}
@@ -152,19 +172,29 @@ static struct command_result *json_deldatastore(struct command *cmd,
struct json_stream *response;
const char *key;
u8 *data;
u64 *generation;
u64 actual_gen;
if (!param(cmd, buffer, params,
p_req("key", param_string, &key),
p_opt("generation", param_u64, &generation),
NULL))
return command_param_failed();
data = wallet_datastore_remove(cmd, cmd->ld->wallet, key);
if (generation) {
data = wallet_datastore_fetch(cmd, cmd->ld->wallet, key,
&actual_gen);
if (data && actual_gen != *generation)
return command_fail(cmd, DATASTORE_DEL_WRONG_GENERATION,
"generation is different");
}
data = wallet_datastore_remove(cmd, cmd->ld->wallet, key, &actual_gen);
if (!data)
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
return command_fail(cmd, DATASTORE_DEL_DOES_NOT_EXIST,
"Key does not exist");
response = json_stream_success(cmd);
json_add_datastore(response, key, data);
json_add_datastore(response, key, data, actual_gen);
return command_success(cmd, response);
}