implement futures based grpc client API

[raakella1]

No description provided.

[szmyd]

This looks pretty good; do we need to update the version so we don't break everyone or...we're okay with temp breakage (MAJOR versus MINOR).

[raakella1]

This looks pretty good; do we need to update the version so we don't break everyone or...we're okay with temp breakage (MAJOR versus MINOR).

Well, the call_unary API that consumers use is unchanged, do we need to make a major version upgrade?

[szmyd]

This looks pretty good; do we need to update the version so we don't break everyone or...we're okay with temp breakage (MAJOR versus MINOR).

Well, the call_unary API that consumers use is unchanged, do we need to make a major version upgrade?

Technically yes because of:

   - virtual void handle_response([[maybe_unused]] bool ok = true) override {
   -     // For unary call, ok is always true, `status_` will indicate error if there are any.
   -     m_cb(m_reply, m_status);
   - }
   + virtual void handle_response(bool ok = true) = 0;
...
   - unary_callback_t< RespT > m_cb;

but i'll leave it up to you to decide if possibly a couple linker issues downstream are fine temporarily.

[codecov-commenter]

Codecov Report

Merging #185 (2a4c4dd) into master (bd9b008) will increase coverage by 0.33%.
The diff coverage is 86.84%.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #185      +/-   ##
==========================================
+ Coverage   62.79%   63.13%   +0.33%     
==========================================
  Files          69       69              
  Lines        4209     4215       +6     
  Branches      531      529       -2     
==========================================
+ Hits         2643     2661      +18     
+ Misses       1332     1321      -11     
+ Partials      234      233       -1     

Components	Coverage Δ
AuthManager	77.77% <ø> (ø)
Cache	25.09% <ø> (+2.49%)	⬆️
FDS	68.39% <ø> (+0.06%)	⬆️
FileWatcher	55.90% <ø> (ø)
Flip	65.67% <ø> (ø)
gRPC	77.66% <86.84%> (-0.31%)	⬇️
Logging	29.33% <ø> (ø)
Metrics	80.54% <ø> (ø)
Options	100.00% <ø> (ø)
Setting	57.98% <ø> (ø)
StatusObject	73.83% <ø> (ø)
Utility	84.91% <ø> (ø)
Version	95.83% <ø> (ø)

[szmyd]

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