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askrene: make "child.c" to be the explicit child entry point.

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The fork logic itself is pretty simple, so do that directly in
askrene.c, and then call into "run_child()" almost as soon as
we do the fork.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2026-02-16 17:39:33 +10:30
parent 3c6504a99e
commit 6903cf2efb
5 changed files with 106 additions and 118 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
plugins/askrene/Makefile
View File

@@ -2,10 +2,10 @@ PLUGIN_ASKRENE_PARENT_SRC := \
plugins/askrene/askrene.c \
plugins/askrene/datastore_wire.c \
plugins/askrene/layer.c \
plugins/askrene/reserve.c \
plugins/askrene/reserve.c
PLUGIN_ASKRENE_CHILD_SRC := \
plugins/askrene/child/entry.c \
plugins/askrene/child/child.c \
plugins/askrene/child/mcf.c \
plugins/askrene/child/dijkstra.c \
plugins/askrene/child/flow.c \

72
plugins/askrene/askrene.c
View File

@@ -8,6 +8,7 @@
*/
#include "config.h"
#include <ccan/array_size/array_size.h>
#include <ccan/noerr/noerr.h>
#include <ccan/tal/grab_file/grab_file.h>
#include <ccan/tal/str/str.h>
#include <common/clock_time.h>
@@ -24,7 +25,8 @@
#include <math.h>
#include <plugins/askrene/askrene.h>
#include <plugins/askrene/child/additional_costs.h>
#include <plugins/askrene/child/entry.h>
#include <plugins/askrene/child/child.h>
#include <plugins/askrene/child/child_log.h>
#include <plugins/askrene/layer.h>
#include <plugins/askrene/reserve.h>
#include <sys/wait.h>
@@ -522,12 +524,11 @@ static struct command_result *do_getroutes(struct command *cmd,
bool include_fees;
const char *err;
struct timemono deadline;
int child_fd, log_fd;
int replyfds[2], logfds[2];
struct router_child *child;
const struct layer **layers;
s8 *biases;
fp16_t *capacities;
int ecode;
/* update the gossmap */
if (gossmap_refresh(askrene->gossmap)) {
@@ -625,31 +626,56 @@ static struct command_result *do_getroutes(struct command *cmd,
child->start = time_mono();
deadline = timemono_add(child->start,
time_from_sec(askrene->route_seconds));
child_fd = fork_router_child(askrene->gossmap,
layers,
biases,
info->additional_costs,
askrene->reserved,
take(capacities),
info->dev_algo == ALGO_SINGLE_PATH,
deadline, srcnode, dstnode, info->amount,
info->maxfee, info->finalcltv, info->maxdelay, info->maxparts,
include_fees,
cmd->id, cmd->filter, &log_fd, &child->pid);
/* Save this, as remove_localmods won't preserve it. */
ecode = errno;
/* We don't need this any more. */
gossmap_remove_localmods(askrene->gossmap, localmods);
if (child_fd == -1) {
err = tal_fmt(tmpctx, "failed to fork: %s", strerror(ecode));
gossmap_remove_localmods(askrene->gossmap, localmods);
if (pipe(replyfds) != 0) {
err = tal_fmt(tmpctx, "failed to create pipes: %s", strerror(errno));
goto fail_broken;
}
if (pipe(logfds) != 0) {
err = tal_fmt(tmpctx, "failed to create pipes: %s", strerror(errno));
close_noerr(replyfds[0]);
close_noerr(replyfds[1]);
goto fail_broken;
}
child->pid = fork();
if (child->pid < 0) {
err = tal_fmt(tmpctx, "failed to fork: %s", strerror(errno));
close_noerr(replyfds[0]);
close_noerr(replyfds[1]);
close_noerr(logfds[0]);
close_noerr(logfds[1]);
goto fail_broken;
}
child->reply_conn = io_new_conn(child, child_fd,
if (child->pid == 0) {
/* We are the child. Run the algo */
close(logfds[0]);
close(replyfds[0]);
set_child_log_fd(logfds[1]);
/* Does not return! */
run_child(askrene->gossmap,
layers,
biases,
info->additional_costs,
askrene->reserved,
take(capacities),
info->dev_algo == ALGO_SINGLE_PATH,
deadline, srcnode, dstnode, info->amount,
info->maxfee, info->finalcltv, info->maxdelay, info->maxparts,
include_fees,
cmd->id, cmd->filter, replyfds[1]);
abort();
}
close(logfds[1]);
close(replyfds[1]);
/* We don't need this any more. */
gossmap_remove_localmods(askrene->gossmap, localmods);
child->reply_conn = io_new_conn(child, replyfds[0],
child_reply_init, child);
child->log_conn = io_new_conn(child, log_fd, child_log_init, child);
child->log_conn = io_new_conn(child, logfds[0], child_log_init, child);
child->cmd = cmd;
list_add_tail(&askrene->children, &child->list);

77
plugins/askrene/child/entry.c → plugins/askrene/child/child.c
View File

@@ -1,18 +1,16 @@
#include "config.h"
#include <assert.h>
#include <ccan/json_out/json_out.h>
#include <ccan/noerr/noerr.h>
#include <ccan/read_write_all/read_write_all.h>
#include <ccan/tal/str/str.h>
#include <common/json_stream.h>
#include <common/route.h>
#include <common/utils.h>
#include <plugins/askrene/child/child.h>
#include <plugins/askrene/child/child_log.h>
#include <plugins/askrene/child/entry.h>
#include <plugins/askrene/child/flow.h>
#include <plugins/askrene/child/mcf.h>
#include <plugins/askrene/child/route_query.h>
#include <unistd.h>
/* A single route. */
struct route {
@@ -195,26 +193,23 @@ static struct route_query *new_route_query(const tal_t *ctx,
return rq;
}
/* Returns fd to child */
int fork_router_child(const struct gossmap *gossmap,
const struct layer **layers,
const s8 *biases,
const struct additional_cost_htable *additional_costs,
struct reserve_htable *reserved,
fp16_t *capacities TAKES,
bool single_path,
struct timemono deadline,
const struct gossmap_node *srcnode,
const struct gossmap_node *dstnode,
struct amount_msat amount, struct amount_msat maxfee,
u32 finalcltv, u32 maxdelay, size_t maxparts,
bool include_fees,
const char *cmd_id,
struct json_filter *cmd_filter,
int *log_fd,
int *child_pid)
void run_child(const struct gossmap *gossmap,
const struct layer **layers,
const s8 *biases,
const struct additional_cost_htable *additional_costs,
struct reserve_htable *reserved,
fp16_t *capacities TAKES,
bool single_path,
struct timemono deadline,
const struct gossmap_node *srcnode,
const struct gossmap_node *dstnode,
struct amount_msat amount, struct amount_msat maxfee,
u32 finalcltv, u32 maxdelay, size_t maxparts,
bool include_fees,
const char *cmd_id,
struct json_filter *cmd_filter,
int replyfd)
{
int replyfds[2], logfds[2];
double probability;
struct flow **flows;
struct route **routes;
@@ -223,35 +218,6 @@ int fork_router_child(const struct gossmap *gossmap,
size_t len;
struct route_query *rq;
if (pipe(replyfds) != 0)
goto parent_fail;
if (pipe(logfds) != 0) {
close_noerr(replyfds[0]);
close_noerr(replyfds[1]);
goto parent_fail;
}
*child_pid = fork();
if (*child_pid < 0) {
close_noerr(replyfds[0]);
close_noerr(replyfds[1]);
close_noerr(logfds[0]);
close_noerr(logfds[1]);
goto parent_fail;
}
if (*child_pid != 0) {
close(logfds[1]);
close(replyfds[1]);
*log_fd = logfds[0];
if (taken(capacities))
tal_free(capacities);
return replyfds[0];
}
/* We are the child. Run the algo */
close(logfds[0]);
close(replyfds[0]);
set_child_log_fd(logfds[1]);
/* We exit below, so we don't bother freeing this */
rq = new_route_query(NULL, gossmap, cmd_id, layers,
biases, additional_costs,
@@ -266,7 +232,7 @@ int fork_router_child(const struct gossmap *gossmap,
maxparts, &flows, &probability);
}
if (err) {
write_all(replyfds[1], err, strlen(err));
write_all(replyfd, err, strlen(err));
/* Non-zero exit tells parent this is an error string. */
exit(1);
}
@@ -305,13 +271,8 @@ int fork_router_child(const struct gossmap *gossmap,
json_stream_close(js, NULL);
p = json_out_contents(js->jout, &len);
if (!write_all(replyfds[1], p, len))
if (!write_all(replyfd, p, len))
abort();
exit(0);
parent_fail:
if (taken(capacities))
tal_free(capacities);
return -1;
}

36
plugins/askrene/child/child.h Normal file
View File

@@ -0,0 +1,36 @@
#ifndef LIGHTNING_PLUGINS_ASKRENE_CHILD_CHILD_H
#define LIGHTNING_PLUGINS_ASKRENE_CHILD_CHILD_H
#include "config.h"
#include <ccan/compiler/compiler.h>
#include <ccan/short_types/short_types.h>
#include <ccan/time/time.h>
#include <common/amount.h>
#include <common/fp16.h>
#include <stdbool.h>
struct additional_cost_htable;
struct gossmap;
struct json_filter;
struct layer;
struct reserve_htable;
/* This is the child. Do the thing. */
void run_child(const struct gossmap *gossmap,
const struct layer **layers,
const s8 *biases,
const struct additional_cost_htable *additional_costs,
struct reserve_htable *reserved,
fp16_t *capacities TAKES,
bool single_path,
struct timemono deadline,
const struct gossmap_node *srcnode,
const struct gossmap_node *dstnode,
struct amount_msat amount, struct amount_msat maxfee,
u32 finalcltv, u32 maxdelay, size_t maxparts,
bool include_fees,
const char *cmd_id,
struct json_filter *cmd_filter,
int reply_fd) NORETURN;
#endif /* LIGHTNING_PLUGINS_ASKRENE_CHILD_CHILD_H */

35
plugins/askrene/child/entry.h
View File

@@ -1,35 +0,0 @@
#ifndef LIGHTNING_PLUGINS_ASKRENE_CHILD_ENTRY_H
#define LIGHTNING_PLUGINS_ASKRENE_CHILD_ENTRY_H
#include "config.h"
#include <ccan/short_types/short_types.h>
#include <ccan/time/time.h>
#include <common/amount.h>
#include <common/fp16.h>
#include <stdbool.h>
struct route_query;
struct gossmap_node;
struct json_filter;
struct layer;
struct reserve_htable;
struct additional_cost_htable;
/* Entry point to the child process. */
int fork_router_child(const struct gossmap *gossmap,
const struct layer **layers,
const s8 *biases,
const struct additional_cost_htable *additional_costs,
struct reserve_htable *reserved,
fp16_t *capacities TAKES,
bool single_path,
struct timemono deadline,
const struct gossmap_node *srcnode,
const struct gossmap_node *dstnode,
struct amount_msat amount, struct amount_msat maxfee,
u32 finalcltv, u32 maxdelay, size_t maxparts,
bool include_fees,
const char *cmd_id,
struct json_filter *cmd_filter,
int *log_fd,
int *child_pid);
#endif /* LIGHTNING_PLUGINS_ASKRENE_CHILD_ENTRY_H */