Minimal change to ensure that the bulky leaseEntry isn't kept in memory.

[ncabatoff]

This is a subset of #10666 that just tries to get the biggest improvement for the smallest change. I re-ran my tests but only used inmem storage for expediency, so I filter out the heap pprof nodes involving BarrierView. Here are the numbers for 1.6.1, #10666, and this PR, all tested with 360000 cert leases:

1.6.1:

Active filters:
   ignore=BarrierView
Showing nodes accounting for 734.27MB, 38.55% of 1904.72MB total
Dropped 194 nodes (cum <= 9.52MB)
Showing top 15 nodes out of 82
      flat  flat%   sum%        cum   cum%
  254.57MB 13.37% 13.37%   328.59MB 17.25%  github.com/hashicorp/vault/builtin/credential/cert.(*backend).pathLogin
  191.05MB 10.03% 23.40%   191.05MB 10.03%  github.com/hashicorp/vault/vault.(*ExpirationManager).leaseTimesForExport (inline)
   47.01MB  2.47% 25.86%   367.46MB 19.29%  github.com/hashicorp/vault/vault.(*ExpirationManager).RegisterAuth
   42.51MB  2.23% 28.10%    42.51MB  2.23%  strings.(*Builder).grow (inline)
   42.50MB  2.23% 30.33%    42.50MB  2.23%  bytes.(*Buffer).String (inline)
   27.62MB  1.45% 31.78%    27.62MB  1.45%  sync.(*Map).dirtyLocked
      26MB  1.37% 33.14%    28.42MB  1.49%  time.AfterFunc
      24MB  1.26% 34.40%   274.44MB 14.41%  github.com/hashicorp/vault/vault.(*ExpirationManager).updatePendingInternal
   14.50MB  0.76% 35.16%       15MB  0.79%  github.com/hashicorp/vault/vault.(*Core).fetchEntityAndDerivedPolicies
   12.50MB  0.66% 35.82%    12.50MB  0.66%  fmt.Sprintf
   12.50MB  0.66% 36.48%    12.50MB  0.66%  github.com/hashicorp/vault/vendor/github.com/hashicorp/vault/sdk/helper/base62.RandomWithReader
   11.50MB   0.6% 37.08%   768.57MB 40.35%  github.com/hashicorp/vault/vault.(*Core).handleLoginRequest
      11MB  0.58% 37.66%    11.50MB   0.6%  github.com/hashicorp/vault/vendor/github.com/hashicorp/vault/sdk/helper/strutil.RemoveDuplicates
      10MB  0.53% 38.18%       10MB  0.53%  math/big.(*Int).Text (inline)
       7MB  0.37% 38.55%        7MB  0.37%  context.(*cancelCtx).Done

This PR:

Active filters:
   ignore=BarrierView
Showing nodes accounting for 345.99MB, 22.80% of 1517.76MB total
Dropped 179 nodes (cum <= 7.59MB)
Showing top 15 nodes out of 92
      flat  flat%   sum%        cum   cum%
  182.05MB 11.99% 11.99%   182.05MB 11.99%  github.com/hashicorp/vault/vault.(*ExpirationManager).leaseTimesForExport (inline)
   46.51MB  3.06% 15.06%    46.51MB  3.06%  strings.(*Builder).grow
   28.50MB  1.88% 16.94%    31.25MB  2.06%  time.AfterFunc
   28.50MB  1.88% 18.81%   271.34MB 17.88%  github.com/hashicorp/vault/vault.(*ExpirationManager).updatePendingInternal
   27.62MB  1.82% 20.63%    27.62MB  1.82%  sync.(*Map).dirtyLocked
       7MB  0.46% 21.10%        7MB  0.46%  context.(*cancelCtx).Done
    4.50MB   0.3% 21.39%    14.09MB  0.93%  context.WithDeadline
    4.50MB   0.3% 21.69%    34.63MB  2.28%  sync.(*Map).Store
       4MB  0.26% 21.95%        4MB  0.26%  context.WithCancel
    3.54MB  0.23% 22.19%     3.54MB  0.23%  github.com/beorn7/perks/quantile.newStream (inline)
    2.75MB  0.18% 22.37%     2.75MB  0.18%  time.startTimer
    2.51MB  0.17% 22.53%     2.51MB  0.17%  bufio.NewReaderSize
    2.50MB  0.16% 22.70%     2.50MB  0.16%  sync.newEntry (inline)
       1MB 0.066% 22.76%     4.55MB   0.3%  github.com/prometheus/client_golang/prometheus.newSummary
    0.50MB 0.033% 22.80%        4MB  0.26%  crypto/x509.parseCertificate

#10666:

Active filters:
   ignore=BarrierView
Showing nodes accounting for 200.68MB, 15.14% of 1325.70MB total
Dropped 93 nodes (cum <= 6.63MB)
Showing top 15 nodes out of 108
      flat  flat%   sum%        cum   cum%
   65.01MB  4.90%  4.90%   132.01MB  9.96%  github.com/hashicorp/vault/vault.(*ExpirationManager).updatePendingInternal
   40.50MB  3.06%  7.96%    40.50MB  3.06%  strings.(*Builder).grow
      33MB  2.49% 10.45%    36.93MB  2.79%  time.AfterFunc
   27.62MB  2.08% 12.53%    27.62MB  2.08%  sync.(*Map).dirtyLocked
       6MB  0.45% 12.98%        6MB  0.45%  context.(*cancelCtx).Done
    4.55MB  0.34% 13.33%     4.55MB  0.34%  github.com/beorn7/perks/quantile.newStream
       4MB   0.3% 13.63%    11.06MB  0.83%  context.WithDeadline
       4MB   0.3% 13.93%    34.13MB  2.57%  sync.(*Map).Store
    3.93MB   0.3% 14.23%     3.93MB   0.3%  time.startTimer
    2.50MB  0.19% 14.42%     2.50MB  0.19%  context.WithCancel
    2.50MB  0.19% 14.61%     2.50MB  0.19%  sync.newEntry (inline)
    2.05MB  0.15% 14.76%     2.05MB  0.15%  github.com/beorn7/perks/quantile.(*stream).merge
       2MB  0.15% 14.91%        2MB  0.15%  encoding/json.(*Decoder).refill
    1.51MB  0.11% 15.02%     1.51MB  0.11%  bufio.NewReaderSize
    1.50MB  0.11% 15.14%     1.50MB  0.11%  net/http.(*http2Framer).readMetaFrame.func1

[mgritter]

This looks very good, but isn't there another ExpireLeaseStrategy around somewhere? Maybe that's enterprise?

[mgritter]

The other function whose signature would have to be altered is expireLeaseStrategyRemoveFromCache in expiration_util_ent.go.

[ncabatoff]

The other function whose signature would have to be altered is expireLeaseStrategyRemoveFromCache in expiration_util_ent.go.

Yup, I'm aware but thanks for the reminder. It's trivial to adapt it as it only cares about leaseID.