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prevent Valkey crash when module is loaded twice #415

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prevent Valkey crash when module is loaded twice #415

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2 changes: 1 addition & 1 deletion vmsdk/src/module.h
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Original file line number Diff line number Diff line change
Expand Up @@ -23,11 +23,11 @@
extern "C" { \
int ValkeyModule_OnLoad(ValkeyModuleCtx *ctx, ValkeyModuleString **argv, \
int argc) { \
vmsdk::TrackCurrentAsMainThread(); \
if (auto status = vmsdk::module::OnLoad(ctx, argv, argc, options); \
status != VALKEYMODULE_OK) { \
return status; \
} \
vmsdk::TrackCurrentAsMainThread(); \
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Maybe it's worth having a "symbol collision" condition that we check prior to calling OnLoad? I guess it is nice if we can keep the main thread tracking before the OnLoad call, so that OnLoad will have it set.

So something like:

absl::Status verifyLoadedOnlyOnce() {
    static bool prev_loaded = false;
    if (prev_loaded) return absl::FailedPrecondition("The module is already loaded");
    prev_loaded = true;
    return absl::OkStatus();
}
...
  int ValkeyModule_OnLoad(ValkeyModuleCtx *ctx, ValkeyModuleString **argv,  \
                          int argc) {                                       \
    VMSDK_RETURN_IF_ERROR(verifyLoadedOnlyOnce()); \
    ... <existing code>

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well, don't use absl::Status as the return type, use a boolean. Don't use VMSDK_RETURN_IF_ERROR.
Put a message in the log directly using a static string (no memory allocations ,please). Then return VALKEYMODULE_ERROR if it fails.

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Sorry, coding in the comment section without an IDE is hard. I thought status was absl::Status here for some reason. But yeah you get the idea

\
if (options.on_load.has_value()) { \
return vmsdk::module::OnLoadDone( \
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