Add trace file path

pageserver/src/config.rs

@@ -354,6 +354,22 @@ impl PageServerConf {
         self.timelines_path(tenantid).join(timelineid.to_string())
     }
 
+    pub fn traces_path(&self) -> PathBuf {
+        self.workdir.join("traces")
+    }
+
+    pub fn trace_path(
+        &self,
+        tenant_id: &ZTenantId,
+        timeline_id: &ZTimelineId,
+        connection_id: &ZTimelineId, // TODO make a new type
+    ) -> PathBuf {
+        self.traces_path()
+            .join(tenant_id.to_string())
+            .join(timeline_id.to_string())
+            .join(connection_id.to_string())
+    }
+
     //
     // Postgres distribution paths
     //

pageserver/src/page_service.rs

@@ -64,21 +64,21 @@ pub enum PagestreamBeMessage {
 }
 
 #[derive(Debug)]
-struct PagestreamExistsRequest {
+pub struct PagestreamExistsRequest {
     latest: bool,
     lsn: Lsn,
     rel: RelTag,
 }
 
 #[derive(Debug)]
-struct PagestreamNblocksRequest {
+pub struct PagestreamNblocksRequest {
     latest: bool,
     lsn: Lsn,
     rel: RelTag,
 }
 
 #[derive(Debug)]
-struct PagestreamGetPageRequest {
+pub struct PagestreamGetPageRequest {
     latest: bool,
     lsn: Lsn,
     rel: RelTag,
@@ -86,34 +86,34 @@ struct PagestreamGetPageRequest {
 }
 
 #[derive(Debug)]
-struct PagestreamDbSizeRequest {
+pub struct PagestreamDbSizeRequest {
     latest: bool,
     lsn: Lsn,
     dbnode: u32,
 }
 
 #[derive(Debug)]
-struct PagestreamExistsResponse {
+pub struct PagestreamExistsResponse {
     exists: bool,
 }
 
 #[derive(Debug)]
-struct PagestreamNblocksResponse {
+pub struct PagestreamNblocksResponse {
     n_blocks: u32,
 }
 
 #[derive(Debug)]
-struct PagestreamGetPageResponse {
+pub struct PagestreamGetPageResponse {
     page: Bytes,
 }
 
 #[derive(Debug)]
-struct PagestreamErrorResponse {
+pub struct PagestreamErrorResponse {
     message: String,
 }
 
 #[derive(Debug)]
-struct PagestreamDbSizeResponse {
+pub struct PagestreamDbSizeResponse {
     db_size: i64,
 }
 
@@ -452,9 +452,9 @@ impl PageServerHandler {
 
         // Make request tracer if needed
         let repo = tenant_mgr::get_repository_for_tenant(tenant_id)?;
-        let trace_read_requests = repo.get_trace_read_requests();
-        let mut tracer = if trace_read_requests {
-            Some(Tracer::new())
+        let mut tracer = if repo.get_trace_read_requests() {
+            let path = repo.conf.trace_path(&tenant_id, &timeline_id, &timeline_id);
+            Some(Tracer::new(path))
         } else {
             None
         };

pageserver/src/trace.rs

@@ -1,6 +1,9 @@
 use crate::page_service::PagestreamFeMessage;
+use std::{fs::File, io::Write, path::PathBuf};
 
-pub struct Tracer {}
+pub struct Tracer {
+    output: File,
+}
 
 impl Drop for Tracer {
     fn drop(&mut self) {
@@ -9,8 +12,10 @@ impl Drop for Tracer {
 }
 
 impl Tracer {
-    pub fn new() -> Self {
-        Tracer {}
+    pub fn new(path: PathBuf) -> Self {
+        Tracer {
+            output: File::create(path).expect("failed to create trace file"),
+        }
     }
 
     pub fn trace(&mut self, _msg: &PagestreamFeMessage) {
@@ -18,6 +23,6 @@ impl Tracer {
     }
 
     pub fn flush(&mut self) {
-        // TODO(now) implement
+        self.output.flush().expect("failed to flush trace file");
     }
 }