Introduce three new APIs that support efficient sharing of portions of packets.
odp_packet_ref_static() creates an alias for a base packet odp_packet_ref() creates a reference to a base packet odp_packet_ref_pkt() creates a reference to a base packet from a supplied header packet In addition, two other APIs simplify working with references odp_packet_is_ref() says whether a packet is a reference odp_packet_unshared_len() gives the sum of data lengths over all unshared packet segments. These are the only bytes of the packet that may be modified safely. Signed-off-by: Bill Fischofer <bill.fischo...@linaro.org> --- Changes in v6: - Miscellaneous formatting corrections - Minor documentation improvements Changes in v5: - Clarified that both input packets to odp_packet_ref_pkt() must be from the same pool and results are undefined if they are not. - Clarified that input(s) to reference create APIs may be references and that implementations are free to perform partial or full packet copies if needed to support such compound references. - Removed odp_packet_has_ref() and redefined odp_packet_is_ref() to indicate simply whether other handles exist that share bytes with this packet. - Modified validation tests to reflect the above changes. Changes in v4: - Bug fixes - Expand validation testing to cover extensions on packets with references Changes in v3: - Rebased to latest API-NEXT - Bug fixes - Eliminate concept of base packets, both references and referenced packets may have head extensions as needed include/odp/api/spec/packet.h | 172 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 171 insertions(+), 1 deletion(-) diff --git a/include/odp/api/spec/packet.h b/include/odp/api/spec/packet.h index 4a86eba..9b6681c 100644 --- a/include/odp/api/spec/packet.h +++ b/include/odp/api/spec/packet.h @@ -256,6 +256,20 @@ uint32_t odp_packet_seg_len(odp_packet_t pkt); uint32_t odp_packet_len(odp_packet_t pkt); /** + * Packet unshared data len + * + * Returns the sum of data lengths over all unshared packet segments. These + * are the only bytes that should be modified by the caller. The rest of the + * packet should be treated as read only. odp_packet_unshared_len() will be + * equal to odp_packet_len() if odp_packet_is_ref() is 0. + * + * @param pkt Packet handle + * + * @return Packet unshared data length + */ +uint32_t odp_packet_unshared_len(odp_packet_t pkt); + +/** * Packet headroom length * * Returns the current packet level headroom length. @@ -795,7 +809,7 @@ uint32_t odp_packet_seg_data_len(odp_packet_t pkt, odp_packet_seg_t seg); * data pointers. Otherwise, all old pointers remain valid. * * The resulting packet is always allocated from the same pool as - * the destination packet. The source packet may have been allocate from + * the destination packet. The source packet may have been allocated from * any pool. * * On failure, both handles remain valid and packets are not modified. @@ -848,6 +862,162 @@ int odp_packet_split(odp_packet_t *pkt, uint32_t len, odp_packet_t *tail); /* * + * References + * ******************************************************** + * + */ + +/** + * Create a static reference to a packet + * + * A static reference is used to obtain an additional handle for referring to + * a packet so that the storage behind it is not freed until all references to + * the packet are freed. This can be used, for example, to support efficient + * retransmission processing. + * + * The intent of a static reference is that both the packet and the returned + * reference to it will be treated as read only after this call. Results are + * undefined if this restriction is not observed. + * + * Static references have restrictions but may have performance advantages on + * some platforms if the caller does not intend to modify the reference + * packet. If modification is needed (e.g., to prefix a unique header onto the + * packet) then odp_packet_ref() or odp_packet_ref_pkt() should be used. + * + * @param pkt Handle of the packet for which a static reference is + * to be created. + * + * @return Handle of the static reference packet + * @retval ODP_PACKET_INVALID Operation failed. pkt remains unchanged. + */ +odp_packet_t odp_packet_ref_static(odp_packet_t pkt); + +/** + * Create a reference to a packet + * + * Create a dynamic reference to a packet starting at a specified byte + * offset. This reference may be used as an argument to header manipulation + * APIs to prefix a unique header onto the shared payload. The storage + * associated with the referenced packet is not freed until all references to + * it are freed, which permits easy multicasting or retransmission processing + * to be performed. Following a successful call, the shared portions of the + * referenced packet packet should be treated as read only. Results are + * undefined if this restriction is not observed. + * + * This operation logically prepends a zero-length header onto the referenced + * packet beginning at the specified offset. This header is always drawn from + * the same pool as the referenced packet. + * + * Because references are unique packets, any bytes pushed onto the head of a + * reference via odp_packet_push_head() or odp_packet_extend_head() are unique + * to this reference and are not seen by the referenced packet or by any other + * reference to the same packet. Similarly, any bytes pushed onto the + * head of the referenced packet are not visible to any reference created + * prior to the push operation. + * + * Note that the existence of references does not in any way change the + * requirement that a single packet handle may only be manipulated by one + * thread at a time. The odp_packet_unshared_len() API may be used to + * determine the number of bytes starting at offset zero that are unique to + * this packet handle. Only these bytes should be considered modifiable. All + * other bytes accessible from this handle should be treated as read only. + * + * The packet used as input to this routine may itself by a reference to some + * other packet. Implementations that are unable to support such compound + * references without copies MAY perform a partial or full packet copy + * operation to return a valid reference in response to this call. + * + * If the caller does not indend to push a header onto either the returned + * reference or the packet being referenced, or otherwise modify either + * packet, the odp_packet_ref_static() API may be used. This may be a more + * efficient means of obtaining another reference to a packet if both will be + * treated as read only. + * + * @param pkt Handle of the packet for which a reference is to be + * created. + * + * @param offset Byte offset in pkt at which the shared reference is to + * begin. This must be in the range 0..odp_packet_len(pkt)-1. + * + * @return Handle of the reference packet + * @retval ODP_PACKET_INVALID Operation failed. pkt remains unchanged. + */ +odp_packet_t odp_packet_ref(odp_packet_t pkt, uint32_t offset); + +/** + * Create a reference to another packet from a header packet + * + * Create a dynamic reference to a packet starting at a specified byte offset + * by prepending a supplied header packet. The resulting reference consists of + * the unshared header followed by the shared referenced packet starting at + * the specified offset. This shared portion should be regarded as read + * only. The storage associated with the shared portion of the reference is + * not freed until all references to it are freed, which permits easy + * multicasting or retransmission processing to be performed. + * + * Because references are unique packets, any bytes pushed onto the head of a + * reference via odp_packet_push_head() or odp_packet_extend_head() are unique + * to this reference and are not seen by the referenced packet or by any other + * reference to the same packet. Similarly, any bytes pushed onto the + * head of the referenced packet are not visible to any reference created + * prior to the push operation. + * + * Note that the existence of references does not in any way change the + * requirement that a single packet handle may only be manipulated by one + * thread at a time. The odp_packet_unshared_len() API may be used to + * determine the number of bytes starting at offset zero that are unique to + * this packet handle. Only these bytes should be considered modifiable. All + * other bytes accessible from this handle should be treated as read only. + * + * Either packet used as input to this routine may itself by a reference to + * some other packet. Implementations that are unable to support such compound + * references without copies MAY perform a partial or full packet copy + * operation to return a valid reference in response to this call. + * + * The packets used as input to this routine should be drawn from the same + * pool. Results are undefined if this restriction is not observed. + * + * odp_packet_pool() on the returned reference returns the pool id of the + * header packet. + * + * @param pkt Handle of the packet for which a reference is to be + * created. + * + * @param offset Byte offset in pkt at which the shared reference is to + * begin. Must be in the range 0..odp_packet_len(pkt)-1. + * + * @param hdr Handle of the header packet to be prefixed onto pkt to create + * the reference. If this is specified as ODP_PACKET_INVALID, + * this call is equivalent to odp_packet_ref(). The supplied hdr + * must be distinct from pkt and results are undefined if an + * attempt is made to create circular references. + * + * @return Handle of the reference packet. This may or may not be the + * same as the input hdr packet. The caller should only use this + * handle since the original hdr packet no longer has any + * independent existence. + * + * @retval ODP_PACKET_INVALID Operation failed. Both pkt and hdr are unchanged. + */ +odp_packet_t odp_packet_ref_pkt(odp_packet_t pkt, uint32_t offset, + odp_packet_t hdr); + +/** + * Test if a packet is a reference + * + * A packet is a reference if any other packet handles exist that share any + * data bytes with this packet. + * + * @param pkt Packet handle + * + * @retval 0 Packet is not a reference. All bytes in this packet are unshared. + * @retval 1 Packet is a reference. One or more other packet handles exist + * that share bytes with this packet. + */ +int odp_packet_is_ref(odp_packet_t pkt); + +/* + * * Copy * ******************************************************** * -- 2.7.4
