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Extend internal API docs, part 2

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Picking up from #8111.

Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
This commit is contained in:
John Ericson 2023-03-26 21:12:25 -04:00
parent 8ae9d66940
commit abd5e7dec0
32 changed files with 640 additions and 359 deletions
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36
src/libstore/worker-protocol.hh
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@ -14,6 +14,10 @@ namespace nix {
#define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)
/**
* Enumeration of all the request types for the "worker protocol", used
* by unix:// and ssh-ng:// stores.
*/
typedef enum {
wopIsValidPath = 1,
wopHasSubstitutes = 3,
@ -74,7 +78,12 @@ typedef enum {
class Store;
struct Source;
/* To guide overloading */
/**
* Used to guide overloading
*
* See https://en.cppreference.com/w/cpp/language/adl for the broader
* concept of what is going on here.
*/
template<typename T>
struct Phantom {};
@ -103,18 +112,19 @@ MAKE_WORKER_PROTO(X_, Y_);
#undef X_
#undef Y_
/* These use the empty string for the null case, relying on the fact
that the underlying types never serialize to the empty string.
We do this instead of a generic std::optional<T> instance because
ordinal tags (0 or 1, here) are a bit of a compatability hazard. For
the same reason, we don't have a std::variant<T..> instances (ordinal
tags 0...n).
We could the generic instances and then these as specializations for
compatability, but that's proven a bit finnicky, and also makes the
worker protocol harder to implement in other languages where such
specializations may not be allowed.
/**
* These use the empty string for the null case, relying on the fact
* that the underlying types never serialize to the empty string.
*
* We do this instead of a generic std::optional<T> instance because
* ordinal tags (0 or 1, here) are a bit of a compatability hazard. For
* the same reason, we don't have a std::variant<T..> instances (ordinal
* tags 0...n).
*
* We could the generic instances and then these as specializations for
* compatability, but that's proven a bit finnicky, and also makes the
* worker protocol harder to implement in other languages where such
* specializations may not be allowed.
*/
MAKE_WORKER_PROTO(, std::optional<StorePath>);
MAKE_WORKER_PROTO(, std::optional<ContentAddress>);