CF_HYDRATION_POLICY_MODIFIER enumeration (cfapi.h)

Allows a sync provider to control how placeholder files should be hydrated by the platform. This is a modifier that can be used with the primary policy: CF_HYDRATION_POLICY_PRIMARY.


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No policy modifier.
This policy modifier offers two guarantees to a sync provider. First, it guarantees that the data returned by the sync provider is always persisted to the disk prior to it being returned to the user application. Second, it allows the sync provider to retrieve the same data it has returned previously to the platform and validate its integrity. Only upon a successful confirmation of the integrity by the sync provider will the platform complete the user I/O request. This modifier helps support end-to-end data integrity at the cost of extra disk I/Os.
This policy modifier grants the platform the permission to not store any data returned by a sync provider on local disks. This policy modifier is ineffective when being combined with CF_HYDRATION_POLICY_MODIFIER_VALIDATION_REQUIRED.
Note  This value is new for Windows 10, version 1803.

This policy modifier grants the platform the permission to dehydrate in-sync cloud file placeholders without the help of sync providers. Without this flag, the platform is not allowed to call CfDehydratePlaceholder directly. Instead, the only supported way to dehydrate a cloud file placeholder is to clear the file’s pinned attribute and set the file’s unpinned attribute. At that point, the actual dehydration will be performed asynchronously by the sync engine after it receives the directory change notification on the two attributes. When this flag is specified, the platform will be allowed to invoke CfDehydratePlaceholder directly on any in-sync cloud file placeholder. It is recommended for sync providers to support auto-dehydration.


In general, modifiers can be mixed and matched with any primary policy (CF_HYDRATION_POLICY_PRIMARY) and other policy modifiers so long as the combination is not self-conflicting.


Minimum supported client Windows 10, version 1709 [desktop apps only]
Minimum supported server Windows Server 2016 [desktop apps only]
Header cfapi.h