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BUG/MEDIUM: support multiple force-persist statements in backends
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George Vine committed May 11, 2024
1 parent 66a0a48 commit dffa08d
Showing 1 changed file with 76 additions and 32 deletions.
108 changes: 76 additions & 32 deletions handlers/backend.go
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Original file line number Diff line number Diff line change
Expand Up @@ -67,37 +67,85 @@ func logDeprecatedFieldsWarning(b *models.Backend) {
if b.HTTPServerClose != "" {
log.Warningf("Field HTTPServerClose is deprecated. Use HTTPConnectionMode.")
}
if b.ForcePersist != nil {
log.Warningf("Field force_persist is deprecated. Use force_persist_list.")
}
if b.IgnorePersist != nil {
log.Warningf("Field ignore_persist is deprecated. Use ignore_persist_list.")
}
}

// handleDeprecatedBackendFields adds backward compatibility support for the field ignore_persist,
// which is deprecated in favour of ignore_persist_list.
// handleDeprecatedBackendFields adds backward compatibility support for the fields
// force_persist and ignore_persist that are deprecated in favour of force_persist_list
// and ignore_persist_list.
func handleDeprecatedBackendFields(method string, payload *models.Backend, onDisk *models.Backend) {
switch method {
case http.MethodGet:
// A fair amount of code duplication in this function is tolerated because this code is expected to be
// short-lived - it should be removed at the end of the sunset period for the deprecated fields.

if method == http.MethodGet {
// Populate force_persist with the first element of force_persist_list if it is present.
if len(payload.ForcePersistList) > 0 {
payload.ForcePersist = &models.BackendForcePersist{
Cond: payload.ForcePersistList[0].Cond,
CondTest: payload.ForcePersistList[0].CondTest,
}
}
// Populate ignore_persist with the first element of ignore_persist_list if it is present.
if len(payload.IgnorePersistList) > 0 {
payload.IgnorePersist = &models.BackendIgnorePersist{
Cond: payload.IgnorePersistList[0].Cond,
CondTest: payload.IgnorePersistList[0].CondTest,
}
}
case http.MethodPost, http.MethodPut:
// Do nothing if ignore_persist is not present in the payload.
if payload.IgnorePersist == nil {
return
}
// If both ignore_persist and ignore_persist_list are present, ignore and remove ignore_persist.
if len(payload.IgnorePersistList) > 0 {
payload.IgnorePersist = nil
return
return
}

if payload.ForcePersist != nil && len(payload.ForcePersistList) == 0 {
if method == http.MethodPost || (method == http.MethodPut && (onDisk == nil || len(onDisk.ForcePersistList) == 0)) {
// Deprecated force_persist is present in a POST payload, or in a PUT payload when force_persist_list does not yet exist in the backend.
// Transform it into force_persist_list with the only element.
payload.ForcePersistList = []*models.ForcePersist{{
Cond: payload.ForcePersist.Cond,
CondTest: payload.ForcePersist.CondTest,
}}
} else {
// Deprecated force_persist is present in a PUT payload, and force_persist_list already exists in the backend.
// Preserve the existing force_persist_list, and add or reposition the submitted force_persist to be its first element.
found := -1
for i, item := range onDisk.ForcePersistList {
if *item.Cond == *payload.ForcePersist.Cond && *item.CondTest == *payload.ForcePersist.CondTest {
found = i
break
}
}
switch found {
case -1:
// force_persist value is not part of existing force_persist_list - insert it in the first position.
payload.ForcePersistList = slices.Insert(onDisk.ForcePersistList, 0, &models.ForcePersist{
Cond: payload.ForcePersist.Cond,
CondTest: payload.ForcePersist.CondTest,
})
case 0:
// force_persist value matches the first element of force_persist_list - preserve it without modification.
payload.ForcePersistList = onDisk.ForcePersistList
default:
// force_persist value matches another element of force_persist_list - move it to the first position.
payload.ForcePersistList = slices.Concat(onDisk.ForcePersistList[found:found+1], onDisk.ForcePersistList[:found], onDisk.ForcePersistList[found+1:])
}
}
}

if method == http.MethodPut && onDisk != nil && len(onDisk.IgnorePersistList) > 0 {
// Preserve ignore_persist_list if it exists prior to modification.
// Add or reposition the value of ignore_persist unless it is already present as the first element.
if payload.IgnorePersist != nil && len(payload.IgnorePersistList) == 0 {
if method == http.MethodPost || (method == http.MethodPut && (onDisk == nil || len(onDisk.IgnorePersistList) == 0)) {
// Deprecated ignore_persist is present in a POST payload, or in a PUT payload when ignore_persist_list does not yet exist in the backend.
// Transform it into ignore_persist_list with the only element.
payload.IgnorePersistList = []*models.IgnorePersist{{
Cond: payload.IgnorePersist.Cond,
CondTest: payload.IgnorePersist.CondTest,
}}
} else {
// Deprecated ignore_persist is present in a PUT payload, and ignore_persist_list already exists in the backend.
// Preserve the existing ignore_persist_list, and add or reposition the submitted ignore_persist to be its first element.
found := -1
for i, item := range onDisk.IgnorePersistList {
if *item.Cond == *payload.IgnorePersist.Cond && *item.CondTest == *payload.IgnorePersist.CondTest {
Expand All @@ -119,17 +167,13 @@ func handleDeprecatedBackendFields(method string, payload *models.Backend, onDis
// ignore_persist value matches another element of ignore_persist_list - move it to the first position.
payload.IgnorePersistList = slices.Concat(onDisk.IgnorePersistList[found:found+1], onDisk.IgnorePersistList[:found], onDisk.IgnorePersistList[found+1:])
}
} else {
// Otherwise, add ignore_persist_list with the value of the provided ignore_persist as its only element.
payload.IgnorePersistList = []*models.IgnorePersist{{
Cond: payload.IgnorePersist.Cond,
CondTest: payload.IgnorePersist.CondTest,
}}
}

// Remove ignore_persist from the payload.
payload.IgnorePersist = nil
}

// Remove force_persist and ignore_persist from the payload - at this point, they were either processed,
// or not present in the payload, or will be ignored because non-deprecated variants were submitted at the same time.
payload.ForcePersist = nil
payload.IgnorePersist = nil
}

// Handle executing the request and returning a response
Expand Down Expand Up @@ -161,8 +205,8 @@ func (h *CreateBackendHandlerImpl) Handle(params backend.CreateBackendParams, pr
return backend.NewCreateBackendDefault(int(*e.Code)).WithPayload(e)
}

// Populate ignore_persist_list if the deprecated ignore_persist field
// is present in the request payload.
// Populate force_persist_list and ignore_persist_list if the corresponding
// deprecated fields force_persist or ignore_persist are present in the request payload.
handleDeprecatedBackendFields(http.MethodPost, params.Data, nil)

err = configuration.CreateBackend(params.Data, t, v)
Expand Down Expand Up @@ -252,7 +296,7 @@ func (h *GetBackendHandlerImpl) Handle(params backend.GetBackendParams, principa
return backend.NewGetBackendDefault(int(*e.Code)).WithPayload(e)
}

// Populate deprecated ignore_persist field in returned response.
// Populate deprecated force_persist and ignore_persist fields in returned response.
handleDeprecatedBackendFields(http.MethodGet, bck, nil)

return backend.NewGetBackendOK().WithPayload(&backend.GetBackendOKBody{Version: v, Data: bck})
Expand All @@ -277,7 +321,7 @@ func (h *GetBackendsHandlerImpl) Handle(params backend.GetBackendsParams, princi
return backend.NewGetBackendsDefault(int(*e.Code)).WithPayload(e)
}

// Populate deprecated ignore_persist field in returned response.
// Populate deprecated force_persist and ignore_persist fields in returned response.
for _, bck := range bcks {
handleDeprecatedBackendFields(http.MethodGet, bck, nil)
}
Expand Down Expand Up @@ -314,9 +358,9 @@ func (h *ReplaceBackendHandlerImpl) Handle(params backend.ReplaceBackendParams,
return backend.NewReplaceBackendDefault(int(*e.Code)).WithPayload(e)
}

// Populate or modify ignore_persist_list if the deprecated ignore_persist field
// is present in the request payload.
if params.Data.IgnorePersist != nil {
// Populate or modify force_persist_list and ignore_persist_list if the corresponding
// deprecated fields force_persist or ignore_persist are present in the request payload.
if params.Data.ForcePersist != nil || params.Data.IgnorePersist != nil {
_, onDisk, confErr := configuration.GetBackend(params.Data.Name, t)
if confErr != nil {
e := misc.HandleError(confErr)
Expand Down

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