Documentation
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Overview ¶
Package viperguard mutex-guards the process-wide global spf13/viper singleton.
spf13/viper has no internal locking of its own: viper.Get*/Set/BindEnv all read or mutate one shared underlying map via deepSearch, and Go maps are not safe for any concurrent read/write access, regardless of which key each goroutine touches -- a BindEnv registering an unrelated key can still race with a concurrent Get of a completely different key. Any code that may run concurrently with other global-viper access (the DAG scheduler's per-node LoadConfig calls, the toolchain's concurrent batch installer, ...) must route through this package's functions instead of calling viper.* directly.
This lives in its own leaf package (no imports of any other Atmos package) specifically so packages low in the dependency graph -- pkg/http and pkg/ui/theme, which pkg/config itself depends on -- can use it without an import cycle. pkg/config.GlobalViper() delegates here rather than keeping a second, independent mutex: two separate locks guarding the same underlying viper singleton would not actually exclude each other, leaving exactly the kind of cross-package race this package exists to close.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func BindEnv ¶
BindEnv binds a Viper key to one or more environment variable names on the global Viper singleton. See viper.BindEnv for the input argument shape.
func GetStringSlice ¶
GetStringSlice returns a clone of key's value coerced to []string: viper's own GetStringSlice can return its value's existing backing array rather than a copy, and handing that out under the lock would let a caller mutate shared Viper state after the lock is released. Returns nil if unset.
func IsSet ¶
IsSet reports whether key has a value from any source, including a registered default: viper.IsSet's underlying find() also checks viper.defaults, so a key registered only via SetDefault also reports true here. It cannot distinguish an explicit value (flag, env, config, override) from a default; callers needing that distinction need a separate check.
func View ¶
func View(fn func(v ViperReader))
View executes fn with a read lock held on the global Viper singleton, giving fn a consistent snapshot for the whole call. Use this instead of separate Get*/IsSet calls whenever a decision combines more than one read (e.g. an IsSet presence check followed by a GetBool value read): each individual function in this package locks and unlocks independently, so a concurrent Set() between two separate calls could let the decision combine one snapshot's presence result with a different snapshot's value.
The callback fn must not call Set, BindEnv, or any other guard writer, directly or transitively: mu.RLock is held for the whole call, and those writers block on mu.Lock until fn returns, so fn calling one deadlocks against itself.
Types ¶
type ViperReader ¶
type ViperReader interface {
// IsSet reports whether key has a value from any source, including a
// registered default (see the package-level IsSet's doc comment for why).
IsSet(key string) bool
// GetBool returns key's value coerced to bool. Returns false if unset.
GetBool(key string) bool
// GetString returns key's value coerced to string. Returns "" if unset.
GetString(key string) string
// GetStringSlice returns key's value coerced to []string, cloned so the
// caller cannot mutate Viper's own backing array. Returns nil if unset.
GetStringSlice(key string) []string
}
ViperReader exposes only *viper.Viper's read methods. View passes this (not *viper.Viper) to its callback, so the callback cannot call a mutator like Set while holding only the read lock -- doing so would race against another concurrent View call's reads, or against Set's write lock, defeating the whole point of View. Extend with more read methods as callers need them; never add a mutator here.
Source Files