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ProcessPriority enum (priority.rs)

Type-safe representation of Windows process priority classes. Provides bidirectional conversion between human-readable string names and Win32 PROCESS_CREATION_FLAGS constants, using a single TABLE constant for DRY lookup logic.

Syntax

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ProcessPriority {
    None,
    Idle,
    BelowNormal,
    Normal,
    AboveNormal,
    High,
    Realtime,
}

Members

Variant String name Win32 constant Value
None "none" (None) N/A — sentinel meaning "do not change"
Idle "idle" IDLE_PRIORITY_CLASS 0x00000040
BelowNormal "below normal" BELOW_NORMAL_PRIORITY_CLASS 0x00004000
Normal "normal" NORMAL_PRIORITY_CLASS 0x00000020
AboveNormal "above normal" ABOVE_NORMAL_PRIORITY_CLASS 0x00008000
High "high" HIGH_PRIORITY_CLASS 0x00000080
Realtime "real time" REALTIME_PRIORITY_CLASS 0x00000100

Methods

as_str

pub fn as_str(&self) -> &'static str

Returns the human-readable string name for this variant (e.g., "above normal"). Returns "unknown" if the variant is not found in TABLE (should not occur for well-constructed values).

as_win_const

pub fn as_win_const(&self) -> Option<PROCESS_CREATION_FLAGS>

Returns the corresponding Win32 PROCESS_CREATION_FLAGS constant, or None for the None variant. A return value of None signals to callers (such as apply_priority) that no priority change should be made.

from_str

pub fn from_str(s: &str) -> Self

Parses a case-insensitive string into a ProcessPriority variant. Unrecognized strings map to ProcessPriority::None. This is used during configuration file parsing.

Parameters

Parameter Type Description
s &str The priority name to parse (e.g., "High", "below normal"). Comparison is case-insensitive.

from_win_const

pub fn from_win_const(val: u32) -> &'static str

Converts a raw Win32 priority class value (as returned by GetPriorityClass) back to a human-readable string name. Returns "unknown" if the value does not match any known constant. This is used in change-log messages to display the "before" state.

Parameters

Parameter Type Description
val u32 The raw PROCESS_CREATION_FLAGS value (.0 field).

Remarks

TABLE-driven design

All four conversion methods operate against a single const TABLE array:

const TABLE: &'static [(Self, &'static str, Option<PROCESS_CREATION_FLAGS>)]

Each entry is a (variant, string_name, optional_win32_constant) tuple. This ensures that adding a new priority level requires only one table entry rather than updates to four separate match arms.

None sentinel

The None variant is not a Windows priority class — it represents the absence of a configured priority. When as_win_const() returns None, apply functions skip the priority-setting step entirely. This is distinct from Normal, which actively sets the priority to NORMAL_PRIORITY_CLASS.

Realtime priority

The Realtime variant maps to REALTIME_PRIORITY_CLASS, which requires SeIncreaseBasePriorityPrivilege and Administrator rights. Using this priority class inappropriately can cause system instability. The string representation uses "real time" (with a space) to match the Windows Task Manager display name.

Requirements
Module src/priority.rs
Callers apply_priority, config parsing (read_config)
Dependencies windows::Win32::System::Threading::PROCESS_CREATION_FLAGS and related constants
Privileges SeIncreaseBasePriorityPrivilege for Realtime

See Also

Topic Link
Apply function that uses this enum apply_priority
IO priority enum IOPriority
Memory priority enum MemoryPriority
Thread priority enum ThreadPriority
Module overview priority.rs
Win32 reference SetPriorityClass

Documented for Commit: facc6e1