1	import Base
2	import ./DurableError.bend as DurableError
3	
4	# Recognizes the host errno values for lock contention.
5	def busy_code(+code: U32) -> Bool:
6	  U32.is_eq(code, 11) || U32.is_eq(code, 35)
7	
8	# Recognizes the host errno for a missing path.
9	def missing_code(+code: U32) -> Bool:
10	  U32.is_eq(code, 2)
11	
12	# Maps non-contention lock errors to NotFound or Io.
13	def classify_nonbusy_lock_error(
14	  missing: Bool,
15	  code: U32,
16	  message: String,
17	  operation: String,
18	  path: String,
19	) -> DurableError.Error:
20	  match missing:
21	    case True{}:
22	      DurableError.Error{DurableError.NotFound{}, operation, path, code, message}
23	    case False{}:
24	      DurableError.Error{DurableError.Io{}, operation, path, code, message}
25	
26	# Maps contention to Busy and retains host details.
27	def classify_lock_busy(busy: Bool, +code: U32, message: String, operation: String, path: String) -> DurableError.Error:
28	  match busy:
29	    case True{}:
30	      DurableError.Error{DurableError.Busy{}, operation, path, code, message}
31	    case False{}:
32	      classify_nonbusy_lock_error(missing_code(code), code, message, operation, path)
33	
34	# Maps lock errors using the pure platform policy.
35	def classify_lock_error(+code: U32, message: String, operation: String, path: String) -> DurableError.Error:
36	  classify_lock_busy(busy_code(code), code, message, operation, path)