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Add detailed information about important parameters for pub & sub sections

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Christophe Bedard 2019-05-27 15:37:33 +02:00
parent f53b52c682
commit 31e971beef
1 changed files with 22 additions and 14 deletions
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doc/ros_2.md
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@ -76,23 +76,27 @@ If intra-process publishing/subscription is enabled, it will be set up after cre
sequenceDiagram sequenceDiagram
participant Component participant Component
participant rclcpp participant rclcpp
participant Publisher
participant rcl participant rcl
participant rmw participant rmw
participant tracetools participant tracetools
Note over rmw: (implementation) Note over rmw: (implementation)
Component->>rclcpp: create_publisher() Component->>rclcpp: create_publisher(topic_name, options, use_intra_process)
Note over rclcpp: allocates rcl_publisher_t handle Note over rclcpp: (...)
rclcpp->>rcl: rcl_publisher_init(out rcl_publisher_t, rcl_node_t, topic_name) rclcpp->>Publisher: Publisher(topic_name, options)
Note over Publisher: allocates rcl_publisher_t handle
Publisher->>rcl: rcl_publisher_init(out rcl_publisher_t, rcl_node_t, topic_name, options)
Note over rcl: populates rcl_publisher_t Note over rcl: populates rcl_publisher_t
rcl->>rmw: rmw_create_publisher(rmw_node_t, topic_name) : rmw_publisher_t rcl->>rmw: rmw_create_publisher(rmw_node_t, topic_name, qos_options) : rmw_publisher_t
Note over rmw: creates rmw_publisher_t handle Note over rmw: creates rmw_publisher_t handle
rcl->>tracetools: TP(rcl_publisher_init, rcl_node_t *, rmw_node_t *, rcl_publisher_t *, topic_name) rcl->>tracetools: TP(rcl_publisher_init, rcl_node_t *, rmw_node_t *, rcl_publisher_t *, topic_name, depth)
opt is intra process opt use_intra_process
rclcpp->>rcl: rcl_publisher_init(...) rclcpp->>Publisher: setup_intra_process()
Publisher->>rcl: rcl_publisher_init(...)
end end
``` ```
@ -102,29 +106,33 @@ Subscription creation is done in a very similar manner.
The componenent calls `create_publisher()`, which ends up creating an `rclcpp::Subscription` object which extends `rclcpp::SubscriptionBase`. The latter allocates an `rcl_subscription_t` handle, fetches its `rcl_node_t` handle, and calls `rcl_subscription_init()` in its constructor. `rcl` does topic name expansion/remapping/validation. It creates an `rmw_subscription_t` handle by calling `rmw_create_subscription()` of the given `rmw` implementation and associates it with the node's `rmw_node_t` handle and the subscription's `rcl_subscription_t` handle. The componenent calls `create_publisher()`, which ends up creating an `rclcpp::Subscription` object which extends `rclcpp::SubscriptionBase`. The latter allocates an `rcl_subscription_t` handle, fetches its `rcl_node_t` handle, and calls `rcl_subscription_init()` in its constructor. `rcl` does topic name expansion/remapping/validation. It creates an `rmw_subscription_t` handle by calling `rmw_create_subscription()` of the given `rmw` implementation and associates it with the node's `rmw_node_t` handle and the subscription's `rcl_subscription_t` handle.
If intra-process publishing/subscription is enabled, it will be set up after creating the subscription object, through a call to `Subscription::setup_intra_process()`, which calls `rcl_subscription_init()`. If intra-process publishing/subscription is enabled, it will be set up after creating the subscription object, through a call to `Subscription::setup_intra_process()`, which calls `rcl_subscription_init()`. This is very similar to a normal (inter-process) subscription, but it sets some flags for later.
```mermaid ```mermaid
sequenceDiagram sequenceDiagram
participant Component participant Component
participant rclcpp participant rclcpp
participant Subscription
participant rcl participant rcl
participant rmw participant rmw
participant tracetools participant tracetools
Note over rmw: (implementation) Note over rmw: (implementation)
Component->>rclcpp: create_subscription() Component->>rclcpp: create_subscription(topic_name, callback, options, use_intra_process)
Note over rclcpp: allocates rcl_subscription_t handle Note over rclcpp: (...)
rclcpp->>rcl: rcl_subscription_init(out rcl_subscription_t, rcl_node_t, topic_name) rclcpp->>Subscription: Subscription(topic_name, callback, options)
Note over Subscription: allocates rcl_subscription_t handle
Subscription->>rcl: rcl_subscription_init(out rcl_subscription_t, rcl_node_t, topic_name, options)
Note over rcl: populates rcl_subscription_t Note over rcl: populates rcl_subscription_t
rcl->>rmw: rmw_create_subscription(rmw_node_t, topic_name) : rmw_subscription_t rcl->>rmw: rmw_create_subscription(rmw_node_t, topic_name, qos_options) : rmw_subscription_t
Note over rmw: creates rmw_subscription_t handle Note over rmw: creates rmw_subscription_t handle
rcl->>tracetools: TP(rcl_subscription_init, rcl_node_t *, rmw_node_t *, rcl_subscription_t *, topic_name) rcl->>tracetools: TP(rcl_subscription_init, rcl_node_t *, rmw_node_t *, rcl_subscription_t *, topic_name)
opt is intra process opt use_intra_process
rclcpp->>rcl: rcl_subscription_init(...) rclcpp->>Subscription: setup_intra_process()
Subscription->>rcl: rcl_subscription_init(...)
end end
rclcpp->>tracetools: TP(rclcpp_subscription_callback_added, rcl_subscription_t *, &any_callback) rclcpp->>tracetools: TP(rclcpp_subscription_callback_added, rcl_subscription_t *, &any_callback)