Struct odbc_api::handles::Environment

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pub struct Environment { /* private fields */ }

Expand description

An Environment is a global context, in which to access data.

Associated with an Environment is any information that is global in nature, such as:

The Environment’s state
The current environment-level diagnostics
The handles of connections currently allocated on the environment
The current stetting of each environment attribute

Implementations

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impl Environment

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pub unsafe fn set_connection_pooling(
scheme: AttrConnectionPooling
) -> SqlResult<()>

Enable or disable (default) connection pooling for ODBC connections. Call this function before creating the ODBC environment for which you want to enable connection pooling.

See: https://docs.microsoft.com/en-us/sql/odbc/reference/develop-app/driver-manager-connection-pooling

Safety

An ODBC driver must be fully thread-safe, and connections must not have thread affinity to support connection pooling. This means the driver is able to handle a call on any thread at any time and is able to connect on one thread, to use the connection on another thread, and to disconnect on a third thread.

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pub fn set_connection_pooling_matching(
&mut self,
matching: AttrCpMatch
) -> SqlResult<()>

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pub fn new() -> SqlResult<Self>

An allocated ODBC Environment handle

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pub fn declare_version(&self, version: AttrOdbcVersion) -> SqlResult<()>

Declares which Version of the ODBC API we want to use. This is the first thing that should be done with any ODBC environment.

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pub fn allocate_connection(&self) -> SqlResult<Connection<'_>>

Allocate a new connection handle. The Connection must not outlive the Environment.

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pub fn as_raw(&self) -> HEnv

Provides access to the raw ODBC environment handle.

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pub unsafe fn drivers_buffer_fill(
 &self,
 direction: FetchOrientation,
 buffer_description: &mut [SqlChar ],
 buffer_attributes: &mut [SqlChar ]
) -> Option<SqlResult<()>>

List drivers descriptions and driver attribute keywords. Returns None to indicate the end of the list.

Callers need to make sure only one thread is iterating over driver information at a time. Method changes environment state. This method would be safe to call via an exclusive &mut reference, yet that would restrict usecases. E.g. requesting information would only be possible before connections borrow a reference.

Parameters

direction: Determines whether the Driver Manager fetches the next driver in the list (FetchOrientation::Next) or whether the search starts from the beginning of the list (FetchOrientation::First).
buffer_description: In case true is returned this buffer is filled with the description of the driver.
buffer_attributes: In case true is returned this buffer is filled with a list of key value attributes. E.g.: "key1=value1\0key2=value2\0\0".

Use Environment::drivers_buffer_len to determine buffer lengths.

See SQLDrivers

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pub unsafe fn drivers_buffer_len(
&self,
direction: FetchOrientation
) -> Option<SqlResult<(i16, i16 )>>

Use together with Environment::drivers_buffer_fill to list drivers descriptions and driver attribute keywords.

Safety

Callers need to make sure only one thread is iterating over driver information at a time. Method changes environment state. This method would be safe to call via an exclusive &mut reference, yet that would restrict usecases. E.g. requesting information would only be possible before connections borrow a reference.

Parameters

direction: Determines whether the Driver Manager fetches the next driver in the list (FetchOrientation::Next) or whether the search starts from the beginning of the list (FetchOrientation::First).

Return

(driver description length, attribute length). Length is in characters minus terminating terminating zero.

See SQLDrivers

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pub unsafe fn data_source_buffer_len(
&self,
direction: FetchOrientation
) -> Option<SqlResult<(i16, i16 )>>

Use together with Environment::data_source_buffer_fill to list drivers descriptions and driver attribute keywords.

Safety

Callers need to make sure only one thread is iterating over data source information at a time. Method changes environment state. This method would be safe to call via an exclusive &mut reference, yet that would restrict usecases. E.g. requesting information would only be possible before connections borrow a reference.

Parameters

direction: Determines whether the Driver Manager fetches the next driver in the list (FetchOrientation::Next) or whether the search starts from the beginning of the list (FetchOrientation::First, FetchOrientation::FirstSystem, FetchOrientation::FirstUser).

Return

(server name length, description length). Length is in characters minus terminating zero.

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pub unsafe fn data_source_buffer_fill(
 &self,
 direction: FetchOrientation,
 buffer_name: &mut [SqlChar ],
 buffer_description: &mut [SqlChar ]
) -> Option<SqlResult<()>>

List drivers descriptions and driver attribute keywords.

Safety

Callers need to make sure only one thread is iterating over data source information at a time. Method changes environment state. This method would be safe to call via an exclusive &mut reference, yet that would restrict usecases. E.g. requesting information would only be possible before connections borrow a reference.

Parameters

direction: Determines whether the Driver Manager fetches the next driver in the list (FetchOrientation::Next) or whether the search starts from the beginning of the list (FetchOrientation::First, FetchOrientation::FirstSystem, FetchOrientation::FirstUser).
buffer_name: In case true is returned this buffer is filled with the name of the datasource.
buffer_description: In case true is returned this buffer is filled with a description of the datasource (i.e. Driver name).