The modules an app ran are freed (research 115's next step): every app's module a Loaded with holds (each snapshot of it, each request read with it); one replaced is retired and freed on the apps thread once no app runs it, every connection thread has begun a pass since (woken for it), and nothing holds it; who keeps a module to ask later whether it is the same asks its serial (core: PureModule.serial, a reader's module_serial, pure_snapshot_module, pure_snapshot_release says it freed; serve: routes, groups, links, bindings, queries, the published snapshot), as an address may come back; a link binds under its receiver's lock, a link naming an input under binding_lock; 030's memory.py: 4,000 changes 0 bytes a change (was 19,284), 4,100 freed; stress.py: readers, view workers, push streams and a body across changes, 586 of 600 loads at a freed module's address, every answer right, ASan 1,000 changes clean; a push group that looked while its app resumed missed the new snapshot (published before the app took requests) and waited for its next save: woken again once it takes them (server_view_workers had failed once under load)

1 files changed, 8 insertions, 1 deletions

diff --git a/core/module.h b/core/module.h
index 43d9ccb..aff6240 100644
--- a/core/module.h
+++ b/core/module.h
@@ -453,6 +453,9 @@ typedef struct {
     uint16_t *signature_record;
     bool calls; /* it has functions: its blocks run in the executor that calls (module.c) */
     uint32_t nesting; /* its loops' deepest nesting (set at load) */
+    /* Which load this is, of the process's: never 0, never the same twice. Who keeps a module's address to ask later
+     * whether it is the same module asks this instead, since another may come to that address once one is freed. */
+    uint64_t serial;
 } PureModule;
 
 /* Whether a state of m is transient (PURE_STATE_TRANSIENT). */
@@ -533,6 +536,7 @@ typedef struct { unsigned char *bytes; size_t used, capacity; } PureArena;
 enum { PURE_LIST_HEARD = 0x10000, PURE_LIST_OUTBOX, PURE_LIST_RUNTIME = 2 };
 typedef struct {
     const PureModule *module;
+    uint64_t module_serial; /* a reader's: its module's serial when it read (the module may since be freed) */
     PureData data;
     /* The arrays of each state (027's 4f-2), sized to the module in one block (states) for the states it was laid out
      * for (laid). */
@@ -792,7 +796,10 @@ void pure_app_checkpointed(PureApp *, PureCheckpoint *, PureResult);
 PureSnapshot *pure_app_snapshot(PureApp *);
 void pure_snapshot_hold(PureSnapshot *);
 /* On any thread; the last reference frees it. */
-void pure_snapshot_release(PureSnapshot *);
+/* Let a reference go: true when it was the last, the snapshot freed. */
+bool pure_snapshot_release(PureSnapshot *);
+/* The module the snapshot's app ran when it was taken. */
+const PureModule *pure_snapshot_module(const PureSnapshot *);
 /* Show a snapshot's states in reader, a zeroed app or a reader before: its
  * views read them while the snapshot is held, with the reader's own arena and
  * row cache (one thread at a time). It applies no events. pure_app_stop frees