PostgreSQL Source Code git master
Macros | Functions | Variables
session.c File Reference
#include "postgres.h"
#include "access/session.h"
#include "storage/lwlock.h"
#include "storage/shm_toc.h"
#include "utils/memutils.h"
#include "utils/typcache.h"
Include dependency graph for session.c:

Go to the source code of this file.

Macros

#define  SESSION_MAGIC   0xabb0fbc9
 
#define  SESSION_DSA_SIZE   0x30000
 
#define  SESSION_KEY_DSA   UINT64CONST(0xFFFFFFFFFFFF0001)
 
#define  SESSION_KEY_RECORD_TYPMOD_REGISTRY   UINT64CONST(0xFFFFFFFFFFFF0002)
 

Functions

void  InitializeSession (void)
 
dsm_handle  GetSessionDsmHandle (void)
 
void  AttachSession (dsm_handle handle)
 
void  DetachSession (void)
 

Variables

Session *  CurrentSession = NULL
 

Macro Definition Documentation

◆ SESSION_DSA_SIZE

#define SESSION_DSA_SIZE   0x30000

Definition at line 39 of file session.c.

◆ SESSION_KEY_DSA

#define SESSION_KEY_DSA   UINT64CONST(0xFFFFFFFFFFFF0001)

Definition at line 44 of file session.c.

◆ SESSION_KEY_RECORD_TYPMOD_REGISTRY

#define SESSION_KEY_RECORD_TYPMOD_REGISTRY   UINT64CONST(0xFFFFFFFFFFFF0002)

Definition at line 45 of file session.c.

◆ SESSION_MAGIC

#define SESSION_MAGIC   0xabb0fbc9

Definition at line 30 of file session.c.

Function Documentation

◆ AttachSession()

void AttachSession ( dsm_handle  handle )

Definition at line 155 of file session.c.

156{
157 dsm_segment *seg;
158 shm_toc *toc;
159 void *dsa_space;
160 void *typmod_registry_space;
161 dsa_area *dsa;
162 MemoryContext old_context;
163
165
166 /* Attach to the DSM segment. */
167 seg = dsm_attach(handle);
168 if (seg == NULL)
169 elog(ERROR, "could not attach to per-session DSM segment");
171
172 /* Attach to the DSA area. */
173 dsa_space = shm_toc_lookup(toc, SESSION_KEY_DSA, false);
174 dsa = dsa_attach_in_place(dsa_space, seg);
175
176 /* Make them available via the current session. */
177 CurrentSession->segment = seg;
178 CurrentSession->area = dsa;
179
180 /* Attach to the shared record typmod registry. */
181 typmod_registry_space =
184 typmod_registry_space);
185
186 /* Remain attached until end of backend or DetachSession(). */
187 dsm_pin_mapping(seg);
188 dsa_pin_mapping(dsa);
189
190 MemoryContextSwitchTo(old_context);
191}
dsa_area * dsa_attach_in_place(void *place, dsm_segment *segment)
Definition: dsa.c:560
void dsa_pin_mapping(dsa_area *area)
Definition: dsa.c:650
void dsm_pin_mapping(dsm_segment *seg)
Definition: dsm.c:915
void * dsm_segment_address(dsm_segment *seg)
Definition: dsm.c:1095
dsm_segment * dsm_attach(dsm_handle h)
Definition: dsm.c:665
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:226
MemoryContext TopMemoryContext
Definition: mcxt.c:166
static MemoryContext MemoryContextSwitchTo(MemoryContext context)
Definition: palloc.h:124
#define SESSION_KEY_RECORD_TYPMOD_REGISTRY
Definition: session.c:45
#define SESSION_KEY_DSA
Definition: session.c:44
#define SESSION_MAGIC
Definition: session.c:30
Session * CurrentSession
Definition: session.c:48
void * shm_toc_lookup(shm_toc *toc, uint64 key, bool noError)
Definition: shm_toc.c:232
shm_toc * shm_toc_attach(uint64 magic, void *address)
Definition: shm_toc.c:64
dsm_segment * segment
Definition: session.h:27
dsa_area * area
Definition: session.h:28
Definition: dsa.c:348
Definition: dsm.c:67
Definition: shm_toc.c:27
void SharedRecordTypmodRegistryAttach(SharedRecordTypmodRegistry *registry)
Definition: typcache.c:2295

References Session::area, CurrentSession, dsa_attach_in_place(), dsa_pin_mapping(), dsm_attach(), dsm_pin_mapping(), dsm_segment_address(), elog, ERROR, MemoryContextSwitchTo(), Session::segment, SESSION_KEY_DSA, SESSION_KEY_RECORD_TYPMOD_REGISTRY, SESSION_MAGIC, SharedRecordTypmodRegistryAttach(), shm_toc_attach(), shm_toc_lookup(), and TopMemoryContext.

Referenced by ParallelWorkerMain().

◆ DetachSession()

void DetachSession ( void  )

Definition at line 201 of file session.c.

202{
203 /* Runs detach hooks. */
205 CurrentSession->segment = NULL;
207 CurrentSession->area = NULL;
208}
void dsa_detach(dsa_area *area)
Definition: dsa.c:1967
void dsm_detach(dsm_segment *seg)
Definition: dsm.c:803

References Session::area, CurrentSession, dsa_detach(), dsm_detach(), and Session::segment.

Referenced by ParallelWorkerMain().

◆ GetSessionDsmHandle()

dsm_handle GetSessionDsmHandle ( void  )

Definition at line 70 of file session.c.

71{
72 shm_toc_estimator estimator;
73 shm_toc *toc;
74 dsm_segment *seg;
75 size_t typmod_registry_size;
76 size_t size;
77 void *dsa_space;
78 void *typmod_registry_space;
79 dsa_area *dsa;
80 MemoryContext old_context;
81
82 /*
83 * If we have already created a session-scope DSM segment in this backend,
84 * return its handle. The same segment will be used for the rest of this
85 * backend's lifetime.
86 */
87 if (CurrentSession->segment != NULL)
89
90 /* Otherwise, prepare to set one up. */
93
94 /* Estimate space for the per-session DSA area. */
95 shm_toc_estimate_keys(&estimator, 1);
97
98 /* Estimate space for the per-session record typmod registry. */
99 typmod_registry_size = SharedRecordTypmodRegistryEstimate();
100 shm_toc_estimate_keys(&estimator, 1);
101 shm_toc_estimate_chunk(&estimator, typmod_registry_size);
102
103 /* Set up segment and TOC. */
104 size = shm_toc_estimate(&estimator);
106 if (seg == NULL)
107 {
108 MemoryContextSwitchTo(old_context);
109
110 return DSM_HANDLE_INVALID;
111 }
114 size);
115
116 /* Create per-session DSA area. */
117 dsa_space = shm_toc_allocate(toc, SESSION_DSA_SIZE);
118 dsa = dsa_create_in_place(dsa_space,
120 LWTRANCHE_PER_SESSION_DSA,
121 seg);
122 shm_toc_insert(toc, SESSION_KEY_DSA, dsa_space);
123
124
125 /* Create session-scoped shared record typmod registry. */
126 typmod_registry_space = shm_toc_allocate(toc, typmod_registry_size);
128 typmod_registry_space, seg, dsa);
130 typmod_registry_space);
131
132 /*
133 * If we got this far, we can pin the shared memory so it stays mapped for
134 * the rest of this backend's life. If we don't make it this far, cleanup
135 * callbacks for anything we installed above (ie currently
136 * SharedRecordTypmodRegistry) will run when the DSM segment is detached
137 * by CurrentResourceOwner so we aren't left with a broken CurrentSession.
138 */
139 dsm_pin_mapping(seg);
140 dsa_pin_mapping(dsa);
141
142 /* Make segment and area available via CurrentSession. */
143 CurrentSession->segment = seg;
144 CurrentSession->area = dsa;
145
146 MemoryContextSwitchTo(old_context);
147
148 return dsm_segment_handle(seg);
149}
#define dsa_create_in_place(place, size, tranche_id, segment)
Definition: dsa.h:122
dsm_handle dsm_segment_handle(dsm_segment *seg)
Definition: dsm.c:1123
dsm_segment * dsm_create(Size size, int flags)
Definition: dsm.c:516
#define DSM_CREATE_NULL_IF_MAXSEGMENTS
Definition: dsm.h:20
#define DSM_HANDLE_INVALID
Definition: dsm_impl.h:58
#define SESSION_DSA_SIZE
Definition: session.c:39
void * shm_toc_allocate(shm_toc *toc, Size nbytes)
Definition: shm_toc.c:88
Size shm_toc_estimate(shm_toc_estimator *e)
Definition: shm_toc.c:263
shm_toc * shm_toc_create(uint64 magic, void *address, Size nbytes)
Definition: shm_toc.c:40
void shm_toc_insert(shm_toc *toc, uint64 key, void *address)
Definition: shm_toc.c:171
#define shm_toc_estimate_chunk(e, sz)
Definition: shm_toc.h:51
#define shm_toc_initialize_estimator(e)
Definition: shm_toc.h:49
#define shm_toc_estimate_keys(e, cnt)
Definition: shm_toc.h:53
Definition: shm_toc.h:44
void SharedRecordTypmodRegistryInit(SharedRecordTypmodRegistry *registry, dsm_segment *segment, dsa_area *area)
Definition: typcache.c:2196
size_t SharedRecordTypmodRegistryEstimate(void)
Definition: typcache.c:2174

References Session::area, CurrentSession, dsa_create_in_place, dsa_pin_mapping(), dsm_create(), DSM_CREATE_NULL_IF_MAXSEGMENTS, DSM_HANDLE_INVALID, dsm_pin_mapping(), dsm_segment_address(), dsm_segment_handle(), MemoryContextSwitchTo(), Session::segment, SESSION_DSA_SIZE, SESSION_KEY_DSA, SESSION_KEY_RECORD_TYPMOD_REGISTRY, SESSION_MAGIC, SharedRecordTypmodRegistryEstimate(), SharedRecordTypmodRegistryInit(), shm_toc_allocate(), shm_toc_create(), shm_toc_estimate(), shm_toc_estimate_chunk, shm_toc_estimate_keys, shm_toc_initialize_estimator, shm_toc_insert(), and TopMemoryContext.

Referenced by InitializeParallelDSM().

◆ InitializeSession()

void InitializeSession ( void  )

Definition at line 54 of file session.c.

55{
57}
void * MemoryContextAllocZero(MemoryContext context, Size size)
Definition: mcxt.c:1263
Definition: session.h:26

References CurrentSession, MemoryContextAllocZero(), and TopMemoryContext.

Referenced by InitPostgres().

Variable Documentation

◆ CurrentSession

Session* CurrentSession = NULL

Definition at line 48 of file session.c.

Referenced by AttachSession(), DetachSession(), find_or_make_matching_shared_tupledesc(), GetSessionDsmHandle(), InitializeSession(), lookup_rowtype_tupdesc_internal(), shared_record_typmod_registry_detach(), SharedRecordTypmodRegistryAttach(), and SharedRecordTypmodRegistryInit().

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